phabricator: add --amend option to phabsend

Previously `hg phabsend` was imitating `hg email` and won't mutate
changesets. That works fine with reviewer-push workflow, reviewers run
`phabread`, `import`.

However, it does not work well with author-push workflow. Namely, the author
needs to run extra commands to get the right commit message, and remove the
local tag after push.

This patch solves those issues by adding the `--amend` option, so local
changesets will have the right commit message, and tags become unnecessary.

Test Plan:
Given the following DAG:

  o  17
  o  16
  | o  15
  | @  14
  |/
  o  13
  o  12

Run `hg phabsend '(13::)-17'  --amend`, check the new DAG looks like:


  o  21
  | o  20
  | @  19
  |/
  o  18
  | o  17
  | x  16
  | x  13
  |/
  o  12

And commit messages are updated to contain the `Differential Revision` lines.
Use `phabread` to make sure Phabricator has the amended node recorded.

Also check `phabsend .` followed by a `phabsend . --amend`, the commit
message will be updated and the tag will be removed.

Differential Revision: https://phab.mercurial-scm.org/D122

contrib/phabricator.py

@@ -1,631 +1,686 b''
 # phabricator.py - simple Phabricator integration
 #
 # Copyright 2017 Facebook, Inc.
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 """simple Phabricator integration
 
 This extension provides a ``phabsend`` command which sends a stack of
 changesets to Phabricator without amending commit messages, and a ``phabread``
 command which prints a stack of revisions in a format suitable
 for :hg:`import`.
 
 By default, Phabricator requires ``Test Plan`` which might prevent some
 changeset from being sent. The requirement could be disabled by changing
 ``differential.require-test-plan-field`` config server side.
 
 Config::
 
     [phabricator]
     # Phabricator URL
     url = https://phab.example.com/
 
     # API token. Get it from https://$HOST/conduit/login/
     token = cli-xxxxxxxxxxxxxxxxxxxxxxxxxxxx
 
     # Repo callsign. If a repo has a URL https://$HOST/diffusion/FOO, then its
     # callsign is "FOO".
     callsign = FOO
 
 """
 
 from __future__ import absolute_import
 
 import json
 import re
 
 from mercurial.node import bin, nullid
 from mercurial.i18n import _
 from mercurial import (
+    cmdutil,
+    context,
     encoding,
     error,
     mdiff,
     obsutil,
     patch,
     registrar,
     scmutil,
     tags,
     url as urlmod,
     util,
 )
 
 cmdtable = {}
 command = registrar.command(cmdtable)
 
 def urlencodenested(params):
     """like urlencode, but works with nested parameters.
 
     For example, if params is {'a': ['b', 'c'], 'd': {'e': 'f'}}, it will be
     flattened to {'a[0]': 'b', 'a[1]': 'c', 'd[e]': 'f'} and then passed to
     urlencode. Note: the encoding is consistent with PHP's http_build_query.
     """
     flatparams = util.sortdict()
     def process(prefix, obj):
         items = {list: enumerate, dict: lambda x: x.items()}.get(type(obj))
         if items is None:
             flatparams[prefix] = obj
         else:
             for k, v in items(obj):
                 if prefix:
                     process('%s[%s]' % (prefix, k), v)
                 else:
                     process(k, v)
     process('', params)
     return util.urlreq.urlencode(flatparams)
 
 def readurltoken(repo):
     """return conduit url, token and make sure they exist
 
     Currently read from [phabricator] config section. In the future, it might
     make sense to read from .arcconfig and .arcrc as well.
     """
     values = []
     section = 'phabricator'
     for name in ['url', 'token']:
         value = repo.ui.config(section, name)
         if not value:
             raise error.Abort(_('config %s.%s is required') % (section, name))
         values.append(value)
     return values
 
 def callconduit(repo, name, params):
     """call Conduit API, params is a dict. return json.loads result, or None"""
     host, token = readurltoken(repo)
     url, authinfo = util.url('/'.join([host, 'api', name])).authinfo()
     urlopener = urlmod.opener(repo.ui, authinfo)
     repo.ui.debug('Conduit Call: %s %s\n' % (url, params))
     params = params.copy()
     params['api.token'] = token
     request = util.urlreq.request(url, data=urlencodenested(params))
     body = urlopener.open(request).read()
     repo.ui.debug('Conduit Response: %s\n' % body)
     parsed = json.loads(body)
     if parsed.get(r'error_code'):
         msg = (_('Conduit Error (%s): %s')
                % (parsed[r'error_code'], parsed[r'error_info']))
         raise error.Abort(msg)
     return parsed[r'result']
 
 @command('debugcallconduit', [], _('METHOD'))
 def debugcallconduit(ui, repo, name):
     """call Conduit API
 
     Call parameters are read from stdin as a JSON blob. Result will be written
     to stdout as a JSON blob.
     """
     params = json.loads(ui.fin.read())
     result = callconduit(repo, name, params)
     s = json.dumps(result, sort_keys=True, indent=2, separators=(',', ': '))
     ui.write('%s\n' % s)
 
 def getrepophid(repo):
     """given callsign, return repository PHID or None"""
     # developer config: phabricator.repophid
     repophid = repo.ui.config('phabricator', 'repophid')
     if repophid:
         return repophid
     callsign = repo.ui.config('phabricator', 'callsign')
     if not callsign:
         return None
     query = callconduit(repo, 'diffusion.repository.search',
                         {'constraints': {'callsigns': [callsign]}})
     if len(query[r'data']) == 0:
         return None
     repophid = encoding.strtolocal(query[r'data'][0][r'phid'])
     repo.ui.setconfig('phabricator', 'repophid', repophid)
     return repophid
 
 _differentialrevisiontagre = re.compile('\AD([1-9][0-9]*)\Z')
 _differentialrevisiondescre = re.compile(
     '^Differential Revision:\s*(?:.*)D([1-9][0-9]*)$', re.M)
 
 def getoldnodedrevmap(repo, nodelist):
     """find previous nodes that has been sent to Phabricator
 
     return {node: (oldnode, Differential diff, Differential Revision ID)}
     for node in nodelist with known previous sent versions, or associated
     Differential Revision IDs. ``oldnode`` and ``Differential diff`` could
     be ``None``.
 
     Examines commit messages like "Differential Revision:" to get the
     association information.
 
     If such commit message line is not found, examines all precursors and their
     tags. Tags with format like "D1234" are considered a match and the node
     with that tag, and the number after "D" (ex. 1234) will be returned.
 
     The ``old node``, if not None, is guaranteed to be the last diff of
     corresponding Differential Revision, and exist in the repo.
     """
     url, token = readurltoken(repo)
     unfi = repo.unfiltered()
     nodemap = unfi.changelog.nodemap
 
     result = {} # {node: (oldnode?, lastdiff?, drev)}
     toconfirm = {} # {node: (force, {precnode}, drev)}
     for node in nodelist:
         ctx = unfi[node]
         # For tags like "D123", put them into "toconfirm" to verify later
         precnodes = list(obsutil.allpredecessors(unfi.obsstore, [node]))
         for n in precnodes:
             if n in nodemap:
                 for tag in unfi.nodetags(n):
                     m = _differentialrevisiontagre.match(tag)
                     if m:
                         toconfirm[node] = (0, set(precnodes), int(m.group(1)))
                         continue
 
         # Check commit message
         m = _differentialrevisiondescre.search(ctx.description())
         if m:
             toconfirm[node] = (1, set(precnodes), int(m.group(1)))
 
     # Double check if tags are genuine by collecting all old nodes from
     # Phabricator, and expect precursors overlap with it.
     if toconfirm:
         drevs = [drev for force, precs, drev in toconfirm.values()]
         alldiffs = callconduit(unfi, 'differential.querydiffs',
                                {'revisionIDs': drevs})
         getnode = lambda d: bin(encoding.unitolocal(
             getdiffmeta(d).get(r'node', ''))) or None
         for newnode, (force, precset, drev) in toconfirm.items():
             diffs = [d for d in alldiffs.values()
                      if int(d[r'revisionID']) == drev]
 
             # "precursors" as known by Phabricator
             phprecset = set(getnode(d) for d in diffs)
 
             # Ignore if precursors (Phabricator and local repo) do not overlap,
             # and force is not set (when commit message says nothing)
             if not force and not bool(phprecset & precset):
                 tagname = 'D%d' % drev
                 tags.tag(repo, tagname, nullid, message=None, user=None,
                          date=None, local=True)
                 unfi.ui.warn(_('D%s: local tag removed - does not match '
                                'Differential history\n') % drev)
                 continue
 
             # Find the last node using Phabricator metadata, and make sure it
             # exists in the repo
             oldnode = lastdiff = None
             if diffs:
                 lastdiff = max(diffs, key=lambda d: int(d[r'id']))
                 oldnode = getnode(lastdiff)
                 if oldnode and oldnode not in nodemap:
                     oldnode = None
 
             result[newnode] = (oldnode, lastdiff, drev)
 
     return result
 
 def getdiff(ctx, diffopts):
     """plain-text diff without header (user, commit message, etc)"""
     output = util.stringio()
     for chunk, _label in patch.diffui(ctx.repo(), ctx.p1().node(), ctx.node(),
                                       None, opts=diffopts):
         output.write(chunk)
     return output.getvalue()
 
 def creatediff(ctx):
     """create a Differential Diff"""
     repo = ctx.repo()
     repophid = getrepophid(repo)
     # Create a "Differential Diff" via "differential.createrawdiff" API
     params = {'diff': getdiff(ctx, mdiff.diffopts(git=True, context=32767))}
     if repophid:
         params['repositoryPHID'] = repophid
     diff = callconduit(repo, 'differential.createrawdiff', params)
     if not diff:
         raise error.Abort(_('cannot create diff for %s') % ctx)
     return diff
 
 def writediffproperties(ctx, diff):
     """write metadata to diff so patches could be applied losslessly"""
     params = {
         'diff_id': diff[r'id'],
         'name': 'hg:meta',
         'data': json.dumps({
             'user': ctx.user(),
             'date': '%d %d' % ctx.date(),
             'node': ctx.hex(),
             'parent': ctx.p1().hex(),
         }),
     }
     callconduit(ctx.repo(), 'differential.setdiffproperty', params)
 
 def createdifferentialrevision(ctx, revid=None, parentrevid=None, oldnode=None,
                                olddiff=None, actions=None):
     """create or update a Differential Revision
 
     If revid is None, create a new Differential Revision, otherwise update
     revid. If parentrevid is not None, set it as a dependency.
 
     If oldnode is not None, check if the patch content (without commit message
     and metadata) has changed before creating another diff.
 
     If actions is not None, they will be appended to the transaction.
     """
     repo = ctx.repo()
     if oldnode:
         diffopts = mdiff.diffopts(git=True, context=1)
         oldctx = repo.unfiltered()[oldnode]
         neednewdiff = (getdiff(ctx, diffopts) != getdiff(oldctx, diffopts))
     else:
         neednewdiff = True
 
     transactions = []
     if neednewdiff:
         diff = creatediff(ctx)
         transactions.append({'type': 'update', 'value': diff[r'phid']})
     else:
         # Even if we don't need to upload a new diff because the patch content
         # does not change. We might still need to update its metadata so
         # pushers could know the correct node metadata.
         assert olddiff
         diff = olddiff
     writediffproperties(ctx, diff)
 
     # Use a temporary summary to set dependency. There might be better ways but
     # I cannot find them for now. But do not do that if we are updating an
     # existing revision (revid is not None) since that introduces visible
     # churns (someone edited "Summary" twice) on the web page.
     if parentrevid and revid is None:
         summary = 'Depends on D%s' % parentrevid
         transactions += [{'type': 'summary', 'value': summary},
                          {'type': 'summary', 'value': ' '}]
 
     if actions:
         transactions += actions
 
     # Parse commit message and update related fields.
     desc = ctx.description()
     info = callconduit(repo, 'differential.parsecommitmessage',
                        {'corpus': desc})
     for k, v in info[r'fields'].items():
         if k in ['title', 'summary', 'testPlan']:
             transactions.append({'type': k, 'value': v})
 
     params = {'transactions': transactions}
     if revid is not None:
         # Update an existing Differential Revision
         params['objectIdentifier'] = revid
 
     revision = callconduit(repo, 'differential.revision.edit', params)
     if not revision:
         raise error.Abort(_('cannot create revision for %s') % ctx)
 
-    return revision
+    return revision, diff
 
 def userphids(repo, names):
     """convert user names to PHIDs"""
     query = {'constraints': {'usernames': names}}
     result = callconduit(repo, 'user.search', query)
     # username not found is not an error of the API. So check if we have missed
     # some names here.
     data = result[r'data']
     resolved = set(entry[r'fields'][r'username'] for entry in data)
     unresolved = set(names) - resolved
     if unresolved:
         raise error.Abort(_('unknown username: %s')
                           % ' '.join(sorted(unresolved)))
     return [entry[r'phid'] for entry in data]
 
 @command('phabsend',
          [('r', 'rev', [], _('revisions to send'), _('REV')),
+          ('', 'amend', False, _('update commit messages')),
           ('', 'reviewer', [], _('specify reviewers')),
           ('', 'confirm', None, _('ask for confirmation before sending'))],
          _('REV [OPTIONS]'))
 def phabsend(ui, repo, *revs, **opts):
     """upload changesets to Phabricator
 
     If there are multiple revisions specified, they will be send as a stack
     with a linear dependencies relationship using the order specified by the
     revset.
 
     For the first time uploading changesets, local tags will be created to
     maintain the association. After the first time, phabsend will check
     obsstore and tags information so it can figure out whether to update an
     existing Differential Revision, or create a new one.
 
+    If --amend is set, update commit messages so they have the
+    ``Differential Revision`` URL, remove related tags. This is similar to what
+    arcanist will do, and is more desired in author-push workflows. Otherwise,
+    use local tags to record the ``Differential Revision`` association.
+
     The --confirm option lets you confirm changesets before sending them. You
     can also add following to your configuration file to make it default
     behaviour.
 
     [phabsend]
     confirm = true
+
+    phabsend will check obsstore and the above association to decide whether to
+    update an existing Differential Revision, or create a new one.
     """
     revs = list(revs) + opts.get('rev', [])
     revs = scmutil.revrange(repo, revs)
 
     if not revs:
         raise error.Abort(_('phabsend requires at least one changeset'))
+    if opts.get('amend'):
+        cmdutil.checkunfinished(repo)
 
     confirm = ui.configbool('phabsend', 'confirm')
     confirm |= bool(opts.get('confirm'))
     if confirm:
         confirmed = _confirmbeforesend(repo, revs)
         if not confirmed:
             raise error.Abort(_('phabsend cancelled'))
 
     actions = []
     reviewers = opts.get('reviewer', [])
     if reviewers:
         phids = userphids(repo, reviewers)
         actions.append({'type': 'reviewers.add', 'value': phids})
 
     # {newnode: (oldnode, olddiff, olddrev}
     oldmap = getoldnodedrevmap(repo, [repo[r].node() for r in revs])
 
+    drevids = [] # [int]
+    diffmap = {} # {newnode: diff}
+
     # Send patches one by one so we know their Differential Revision IDs and
     # can provide dependency relationship
     lastrevid = None
     for rev in revs:
         ui.debug('sending rev %d\n' % rev)
         ctx = repo[rev]
 
         # Get Differential Revision ID
         oldnode, olddiff, revid = oldmap.get(ctx.node(), (None, None, None))
-        if oldnode != ctx.node():
+        if oldnode != ctx.node() or opts.get('amend'):
             # Create or update Differential Revision
-            revision = createdifferentialrevision(ctx, revid, lastrevid,
-                                                  oldnode, olddiff, actions)
+            revision, diff = createdifferentialrevision(
+                ctx, revid, lastrevid, oldnode, olddiff, actions)
+            diffmap[ctx.node()] = diff
             newrevid = int(revision[r'object'][r'id'])
             if revid:
                 action = _('updated')
             else:
                 action = _('created')
 
-            # Create a local tag to note the association
-            tagname = 'D%d' % newrevid
-            tags.tag(repo, tagname, ctx.node(), message=None, user=None,
-                     date=None, local=True)
+            # Create a local tag to note the association, if commit message
+            # does not have it already
+            m = _differentialrevisiondescre.search(ctx.description())
+            if not m or int(m.group(1)) != newrevid:
+                tagname = 'D%d' % newrevid
+                tags.tag(repo, tagname, ctx.node(), message=None, user=None,
+                         date=None, local=True)
         else:
             # Nothing changed. But still set "newrevid" so the next revision
             # could depend on this one.
             newrevid = revid
             action = _('skipped')
 
         ui.write(_('D%s: %s - %s: %s\n') % (newrevid, action, ctx,
                                             ctx.description().split('\n')[0]))
+        drevids.append(newrevid)
         lastrevid = newrevid
 
+    # Update commit messages and remove tags
+    if opts.get('amend'):
+        unfi = repo.unfiltered()
+        drevs = callconduit(repo, 'differential.query', {'ids': drevids})
+        with repo.wlock(), repo.lock(), repo.transaction('phabsend'):
+            wnode = unfi['.'].node()
+            mapping = {} # {oldnode: [newnode]}
+            for i, rev in enumerate(revs):
+                old = unfi[rev]
+                drevid = drevids[i]
+                drev = [d for d in drevs if int(d[r'id']) == drevid][0]
+                newdesc = getdescfromdrev(drev)
+                # Make sure commit message contain "Differential Revision"
+                if old.description() != newdesc:
+                    parents = [
+                        mapping.get(old.p1().node(), (old.p1(),))[0],
+                        mapping.get(old.p2().node(), (old.p2(),))[0],
+                    ]
+                    new = context.metadataonlyctx(
+                        repo, old, parents=parents, text=newdesc,
+                        user=old.user(), date=old.date(), extra=old.extra())
+                    newnode = new.commit()
+                    mapping[old.node()] = [newnode]
+                    # Update diff property
+                    writediffproperties(unfi[newnode], diffmap[old.node()])
+                # Remove local tags since it's no longer necessary
+                tagname = 'D%d' % drevid
+                if tagname in repo.tags():
+                    tags.tag(repo, tagname, nullid, message=None, user=None,
+                             date=None, local=True)
+            scmutil.cleanupnodes(repo, mapping, 'phabsend')
+            if wnode in mapping:
+                unfi.setparents(mapping[wnode][0])
+
 # Map from "hg:meta" keys to header understood by "hg import". The order is
 # consistent with "hg export" output.
 _metanamemap = util.sortdict([(r'user', 'User'), (r'date', 'Date'),
                               (r'node', 'Node ID'), (r'parent', 'Parent ')])
 
 def _confirmbeforesend(repo, revs):
     ui = repo.ui
     for rev in revs:
         ctx = repo[rev]
         desc = ctx.description().splitlines()[0]
         ui.write(('%d: ' % rev), label='phabsend.revnumber')
         ui.write(('%s\n' % desc), label='phabsend.desc')
 
     if ui.promptchoice(_('Phabsend the above changes (yn)?'
                             '$$ &Yes $$ &No')):
         return False
 
     return True
 
 def querydrev(repo, params, stack=False):
     """return a list of "Differential Revision" dicts
 
     params is the input of "differential.query" API, and is expected to match
     just a single Differential Revision.
 
     A "Differential Revision dict" looks like:
 
         {
             "id": "2",
             "phid": "PHID-DREV-672qvysjcczopag46qty",
             "title": "example",
             "uri": "https://phab.example.com/D2",
             "dateCreated": "1499181406",
             "dateModified": "1499182103",
             "authorPHID": "PHID-USER-tv3ohwc4v4jeu34otlye",
             "status": "0",
             "statusName": "Needs Review",
             "properties": [],
             "branch": null,
             "summary": "",
             "testPlan": "",
             "lineCount": "2",
             "activeDiffPHID": "PHID-DIFF-xoqnjkobbm6k4dk6hi72",
             "diffs": [
               "3",
               "4",
             ],
             "commits": [],
             "reviewers": [],
             "ccs": [],
             "hashes": [],
             "auxiliary": {
               "phabricator:projects": [],
               "phabricator:depends-on": [
                 "PHID-DREV-gbapp366kutjebt7agcd"
               ]
             },
             "repositoryPHID": "PHID-REPO-hub2hx62ieuqeheznasv",
             "sourcePath": null
         }
 
     If stack is True, return a list of "Differential Revision dict"s in an
     order that the latter ones depend on the former ones. Otherwise, return a
     list of a unique "Differential Revision dict".
     """
     prefetched = {} # {id or phid: drev}
     def fetch(params):
         """params -> single drev or None"""
         key = (params.get(r'ids') or params.get(r'phids') or [None])[0]
         if key in prefetched:
             return prefetched[key]
         # Otherwise, send the request. If we're fetching a stack, be smarter
         # and fetch more ids in one batch, even if it could be unnecessary.
         batchparams = params
         if stack and len(params.get(r'ids', [])) == 1:
             i = int(params[r'ids'][0])
             # developer config: phabricator.batchsize
             batchsize = repo.ui.configint('phabricator', 'batchsize', 12)
             batchparams = {'ids': range(max(1, i - batchsize), i + 1)}
         drevs = callconduit(repo, 'differential.query', batchparams)
         # Fill prefetched with the result
         for drev in drevs:
             prefetched[drev[r'phid']] = drev
             prefetched[int(drev[r'id'])] = drev
         if key not in prefetched:
             raise error.Abort(_('cannot get Differential Revision %r') % params)
         return prefetched[key]
 
     visited = set()
     result = []
     queue = [params]
     while queue:
         params = queue.pop()
         drev = fetch(params)
         if drev[r'id'] in visited:
             continue
         visited.add(drev[r'id'])
         result.append(drev)
         if stack:
             auxiliary = drev.get(r'auxiliary', {})
             depends = auxiliary.get(r'phabricator:depends-on', [])
             for phid in depends:
                 queue.append({'phids': [phid]})
     result.reverse()
     return result
 
 def getdescfromdrev(drev):
     """get description (commit message) from "Differential Revision"
 
     This is similar to differential.getcommitmessage API. But we only care
     about limited fields: title, summary, test plan, and URL.
     """
     title = drev[r'title']
     summary = drev[r'summary'].rstrip()
     testplan = drev[r'testPlan'].rstrip()
     if testplan:
         testplan = 'Test Plan:\n%s' % testplan
     uri = 'Differential Revision: %s' % drev[r'uri']
     return '\n\n'.join(filter(None, [title, summary, testplan, uri]))
 
 def getdiffmeta(diff):
     """get commit metadata (date, node, user, p1) from a diff object
 
     The metadata could be "hg:meta", sent by phabsend, like:
 
         "properties": {
           "hg:meta": {
             "date": "1499571514 25200",
             "node": "98c08acae292b2faf60a279b4189beb6cff1414d",
             "user": "Foo Bar <[e-mail]>",
             "parent": "6d0abad76b30e4724a37ab8721d630394070fe16"
           }
         }
 
     Or converted from "local:commits", sent by "arc", like:
 
         "properties": {
           "local:commits": {
             "98c08acae292b2faf60a279b4189beb6cff1414d": {
               "author": "Foo Bar",
               "time": 1499546314,
               "branch": "default",
               "tag": "",
               "commit": "98c08acae292b2faf60a279b4189beb6cff1414d",
               "rev": "98c08acae292b2faf60a279b4189beb6cff1414d",
               "local": "1000",
               "parents": ["6d0abad76b30e4724a37ab8721d630394070fe16"],
               "summary": "...",
               "message": "...",
               "authorEmail": "[e-mail]"
             }
           }
         }
 
     Note: metadata extracted from "local:commits" will lose time zone
     information.
     """
     props = diff.get(r'properties') or {}
     meta = props.get(r'hg:meta')
     if not meta and props.get(r'local:commits'):
         commit = sorted(props[r'local:commits'].values())[0]
         meta = {
             r'date': r'%d 0' % commit[r'time'],
             r'node': commit[r'rev'],
             r'user': r'%s <%s>' % (commit[r'author'], commit[r'authorEmail']),
         }
         if len(commit.get(r'parents', ())) >= 1:
             meta[r'parent'] = commit[r'parents'][0]
     return meta or {}
 
 def readpatch(repo, params, write, stack=False):
     """generate plain-text patch readable by 'hg import'
 
     write is usually ui.write. params is passed to "differential.query". If
     stack is True, also write dependent patches.
     """
     # Differential Revisions
     drevs = querydrev(repo, params, stack)
 
     # Prefetch hg:meta property for all diffs
     diffids = sorted(set(max(int(v) for v in drev[r'diffs']) for drev in drevs))
     diffs = callconduit(repo, 'differential.querydiffs', {'ids': diffids})
 
     # Generate patch for each drev
     for drev in drevs:
         repo.ui.note(_('reading D%s\n') % drev[r'id'])
 
         diffid = max(int(v) for v in drev[r'diffs'])
         body = callconduit(repo, 'differential.getrawdiff', {'diffID': diffid})
         desc = getdescfromdrev(drev)
         header = '# HG changeset patch\n'
 
         # Try to preserve metadata from hg:meta property. Write hg patch
         # headers that can be read by the "import" command. See patchheadermap
         # and extract in mercurial/patch.py for supported headers.
         meta = getdiffmeta(diffs[str(diffid)])
         for k in _metanamemap.keys():
             if k in meta:
                 header += '# %s %s\n' % (_metanamemap[k], meta[k])
 
         content = '%s%s\n%s' % (header, desc, body)
         write(encoding.unitolocal(content))
 
 @command('phabread',
          [('', 'stack', False, _('read dependencies'))],
          _('REVID [OPTIONS]'))
 def phabread(ui, repo, revid, **opts):
     """print patches from Phabricator suitable for importing
 
     REVID could be a Differential Revision identity, like ``D123``, or just the
     number ``123``, or a full URL like ``https://phab.example.com/D123``.
 
     If --stack is given, follow dependencies information and read all patches.
     """
     try:
         revid = int(revid.split('/')[-1].replace('D', ''))
     except ValueError:
         raise error.Abort(_('invalid Revision ID: %s') % revid)
     readpatch(repo, {'ids': [revid]}, ui.write, opts.get('stack'))