fetch: switch the default parent used for a merge

This treats newly pulled changes as authoritative, and local changes as
the "satellite" changes.

The prior default behaviour is still available, via the --switch-parent
option.

hgext/fetch.py

@@ -1,102 +1,121
 # fetch.py - pull and merge remote changes
 #
 # Copyright 2006 Vadim Gelfer <[e-mail]>
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
 from mercurial.i18n import _
 from mercurial.node import *
 from mercurial import commands, cmdutil, hg, node, util
 
 def fetch(ui, repo, source='default', **opts):
     '''Pull changes from a remote repository, merge new changes if needed.
 
     This finds all changes from the repository at the specified path
     or URL and adds them to the local repository.
 
     If the pulled changes add a new head, the head is automatically
     merged, and the result of the merge is committed.  Otherwise, the
-    working directory is updated.
+    working directory is updated to include the new changes.
+
+    When a merge occurs, the newly pulled changes are assumed to be
+    "authoritative".  The head of the new changes is used as the first
+    parent, with local changes as the second.  To switch the merge
+    order, use --switch-parent.
 
     See 'hg help dates' for a list of formats valid for -d/--date.
     '''
 
     def postincoming(other, modheads):
         if modheads == 0:
             return 0
         if modheads == 1:
             return hg.clean(repo, repo.changelog.tip())
         newheads = repo.heads(parent)
         newchildren = [n for n in repo.heads(parent) if n != parent]
         newparent = parent
         if newchildren:
             newparent = newchildren[0]
             hg.clean(repo, newparent)
         newheads = [n for n in repo.heads() if n != newparent]
-        err = False
-        if newheads:
-            ui.status(_('merging with new head %d:%s\n') %
-                      (repo.changelog.rev(newheads[0]), short(newheads[0])))
-            err = hg.merge(repo, newheads[0], remind=False)
-        if not err and len(newheads) > 1:
+        if len(newheads) > 1:
             ui.status(_('not merging with %d other new heads '
                         '(use "hg heads" and "hg merge" to merge them)') %
                       (len(newheads) - 1))
+            return
+        err = False
+        if newheads:
+            # By default, we consider the repository we're pulling
+            # *from* as authoritative, so we merge our changes into
+            # theirs.
+            if opts['switch_parent']:
+                firstparent, secondparent = newparent, newheads[0]
+            else:
+                firstparent, secondparent = newheads[0], newparent
+                ui.status(_('updating to %d:%s\n') %
+                          (repo.changelog.rev(firstparent),
+                           short(firstparent)))
+            hg.clean(repo, firstparent)
+            ui.status(_('merging with %d:%s\n') %
+                      (repo.changelog.rev(secondparent), short(secondparent)))
+            err = hg.merge(repo, secondparent, remind=False)
         if not err:
             mod, add, rem = repo.status()[:3]
             message = (cmdutil.logmessage(opts) or
                        (_('Automated merge with %s') %
                         util.removeauth(other.url())))
             n = repo.commit(mod + add + rem, message,
                             opts['user'], opts['date'],
                             force_editor=opts.get('force_editor'))
             ui.status(_('new changeset %d:%s merges remote changes '
                         'with local\n') % (repo.changelog.rev(n),
                                            short(n)))
+
     def pull():
         cmdutil.setremoteconfig(ui, opts)
 
         other = hg.repository(ui, ui.expandpath(source))
         ui.status(_('pulling from %s\n') %
                   util.hidepassword(ui.expandpath(source)))
         revs = None
         if opts['rev'] and not other.local():
             raise util.Abort(_("fetch -r doesn't work for remote repositories yet"))
         elif opts['rev']:
             revs = [other.lookup(rev) for rev in opts['rev']]
         modheads = repo.pull(other, heads=revs)
         return postincoming(other, modheads)
 
     date = opts.get('date')
     if date:
         opts['date'] = util.parsedate(date)
 
     parent, p2 = repo.dirstate.parents()
     if parent != repo.changelog.tip():
         raise util.Abort(_('working dir not at tip '
                            '(use "hg update" to check out tip)'))
     if p2 != nullid:
         raise util.Abort(_('outstanding uncommitted merge'))
     wlock = lock = None
     try:
         wlock = repo.wlock()
         lock = repo.lock()
         mod, add, rem = repo.status()[:3]
         if mod or add or rem:
             raise util.Abort(_('outstanding uncommitted changes'))
         if len(repo.heads()) > 1:
             raise util.Abort(_('multiple heads in this repository '
                                '(use "hg heads" and "hg merge" to merge)'))
         return pull()
     finally:
         del lock, wlock
 
 cmdtable = {
     'fetch':
         (fetch,
         [('r', 'rev', [], _('a specific revision you would like to pull')),
          ('f', 'force-editor', None, _('edit commit message')),
+         ('', 'switch-parent', None, _('switch parents when merging')),
         ] + commands.commitopts + commands.commitopts2 + commands.remoteopts,
         _('hg fetch [SOURCE]')),
 }

tests/test-fetch

@@ -1,39 +1,52
 #!/bin/sh
 
 echo "[extensions]" >> $HGRCPATH
 echo "fetch=" >> $HGRCPATH
 
 hg init a
 echo a > a/a
 hg --cwd a commit -d '1 0' -Ama
 
 hg clone a b
 hg clone a c
 
 echo b > a/b
 hg --cwd a commit -d '2 0' -Amb
 hg --cwd a parents -q
 
 echo % should pull one change
 hg --cwd b fetch ../a
 hg --cwd b parents -q
 
 echo c > c/c
 hg --cwd c commit -d '3 0' -Amc
 
 hg clone c d
 hg clone c e
 
+echo % should merge c into a
 hg --cwd c fetch -d '4 0' -m 'automated merge' ../a
 ls c
 
 hg --cwd a serve -a localhost -p $HGPORT -d --pid-file=hg.pid
 cat a/hg.pid >> "$DAEMON_PIDS"
 
 echo '% fetch over http, no auth'
 hg --cwd d fetch -d '5 0' http://localhost:$HGPORT/
 hg --cwd d tip --template '{desc}\n'
 
 echo '% fetch over http with auth (should be hidden in desc)'
 hg --cwd e fetch -d '5 0' http://user:password@localhost:$HGPORT/
 hg --cwd e tip --template '{desc}\n'
+
+hg clone a f
+hg clone a g
+
+echo f > f/f
+hg --cwd f ci -d '6 0' -Amf
+
+echo g > g/g
+hg --cwd g ci -d '6 0' -Amg
+
+echo % should merge f into g
+hg --cwd g fetch --switch ../f

tests/test-fetch.out

@@ -1,51 +1,73
 adding a
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 adding b
 1:97d72e5f12c7
 % should pull one change
 pulling from ../a
 searching for changes
 adding changesets
 adding manifests
 adding file changes
 added 1 changesets with 1 changes to 1 files
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 1:97d72e5f12c7
 adding c
 2 files updated, 0 files merged, 0 files removed, 0 files unresolved
 2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+% should merge c into a
 pulling from ../a
 searching for changes
 adding changesets
 adding manifests
 adding file changes
 added 1 changesets with 1 changes to 1 files (+1 heads)
-merging with new head 2:97d72e5f12c7
+updating to 2:97d72e5f12c7
+1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+merging with 1:5e056962225c
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 new changeset 3:cd3a41621cf0 merges remote changes with local
 a
 b
 c
 % fetch over http, no auth
 pulling from http://localhost:20059/
 searching for changes
 adding changesets
 adding manifests
 adding file changes
 added 1 changesets with 1 changes to 1 files (+1 heads)
-merging with new head 2:97d72e5f12c7
+updating to 2:97d72e5f12c7
+1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+merging with 1:5e056962225c
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 new changeset 3:0b6439e938f9 merges remote changes with local
 Automated merge with http://localhost:20059/
 % fetch over http with auth (should be hidden in desc)
 pulling from http://user:***@localhost:20059/
 searching for changes
 adding changesets
 adding manifests
 adding file changes
 added 1 changesets with 1 changes to 1 files (+1 heads)
-merging with new head 2:97d72e5f12c7
+updating to 2:97d72e5f12c7
+1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+merging with 1:5e056962225c
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 new changeset 3:0b6439e938f9 merges remote changes with local
 Automated merge with http://localhost:20059/
+2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+adding f
+adding g
+% should merge f into g
+pulling from ../f
+searching for changes
+adding changesets
+adding manifests
+adding file changes
+added 1 changesets with 1 changes to 1 files (+1 heads)
+0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+merging with 3:cc6a3744834d
+1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+new changeset 4:96d2275e70b4 merges remote changes with local