lfs: infer the blob store URL from an explicit push dest or default-push

Unlike pull, the blobs are uploaded within the exchange.push() window, so simply
wrap it and swap in a properly configured remote store.  The '_subtoppath' field
shouldn't be available during this window, but give the passed path priority for
clarity.

At one point I hit an AttributeError in one of the convert tests when trying to
save the original remote blobstore when the swap was run unconditionally.  I
wrapped it in a util.safehasattr(), but then today I wasn't able to reproduce
it.  But now the whole thing is tucked under the requirement guard because
without the requirement, there are no blobs in the repo, even if the extension
is loaded.

hgext/lfs/__init__.py

@@ -87,9 +87,9 b' Configs::'
     #   git-lfs endpoint
     # - file:///tmp/path
     #   local filesystem, usually for testing
-    # if unset, lfs will assume the repository at ``paths.default`` also handles
-    # blob storage for http(s) URLs.  Otherwise, lfs will prompt to set this
-    # when it must use this value.
+    # if unset, lfs will assume the remote repository also handles blob storage
+    # for http(s) URLs.  Otherwise, lfs will prompt to set this when it must
+    # use this value.
     # (default: unset)
     url = https://example.com/repo.git/info/lfs
 

hgext/lfs/blobstore.py

@@ -529,7 +529,7 b' def _verify(oid, content):'
         raise error.Abort(_('detected corrupt lfs object: %s') % oid,
                           hint=_('run hg verify'))
 
-def remote(repo):
+def remote(repo, remote=None):
     """remotestore factory. return a store in _storemap depending on config
 
     If ``lfs.url`` is specified, use that remote endpoint.  Otherwise, try to
@@ -541,7 +541,9 b' def remote(repo):'
     """
     url = util.url(repo.ui.config('lfs', 'url') or '')
     if url.scheme is None:
-        if util.safehasattr(repo, '_subtoppath'):
+        if remote:
+            defaulturl = util.url(remote)
+        elif util.safehasattr(repo, '_subtoppath'):
             # The pull command sets this during the optional update phase, which
             # tells exactly where the pull originated, whether 'paths.default'
             # or explicit.

hgext/lfs/wrapper.py

@@ -289,7 +289,8 b' def prepush(pushop):'
     return uploadblobsfromrevs(pushop.repo, pushop.outgoing.missing)
 
 def push(orig, repo, remote, *args, **kwargs):
-    """bail on push if the extension isn't enabled on remote when needed"""
+    """bail on push if the extension isn't enabled on remote when needed, and
+    update the remote store based on the destination path."""
     if 'lfs' in repo.requirements:
         # If the remote peer is for a local repo, the requirement tests in the
         # base class method enforce lfs support.  Otherwise, some revisions in
@@ -300,7 +301,18 b' def push(orig, repo, remote, *args, **kw'
             m = _("required features are not supported in the destination: %s")
             raise error.Abort(m % 'lfs',
                               hint=_('enable the lfs extension on the server'))
-    return orig(repo, remote, *args, **kwargs)
+
+        # Repositories where this extension is disabled won't have the field.
+        # But if there's a requirement, then the extension must be loaded AND
+        # there may be blobs to push.
+        remotestore = repo.svfs.lfsremoteblobstore
+        try:
+            repo.svfs.lfsremoteblobstore = blobstore.remote(repo, remote.url())
+            return orig(repo, remote, *args, **kwargs)
+        finally:
+            repo.svfs.lfsremoteblobstore = remotestore
+    else:
+        return orig(repo, remote, *args, **kwargs)
 
 def writenewbundle(orig, ui, repo, source, filename, bundletype, outgoing,
                    *args, **kwargs):

tests/test-lfs-serve.t

@@ -242,7 +242,23 b' lfs content, and the extension enabled.'
   $ echo 'this is another lfs file' > lfs2.txt
   $ hg ci -Aqm 'lfs file with lfs client'
 
-  $ hg push -q
+  $ hg --config paths.default= push -v http://localhost:$HGPORT
+  pushing to http://localhost:$HGPORT/
+  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
+  searching for changes
+  remote has heads on branch 'default' that are not known locally: 8374dc4052cb
+  lfs: uploading a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de (25 bytes)
+  lfs: processed: a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de
+  lfs: uploaded 1 files (25 bytes)
+  1 changesets found
+  uncompressed size of bundle content:
+       206 (changelog)
+       172 (manifests)
+       275  lfs2.txt
+  remote: adding changesets
+  remote: adding manifests
+  remote: adding file changes
+  remote: added 1 changesets with 1 changes to 1 files
   $ grep 'lfs' .hg/requires $SERVER_REQUIRES
   .hg/requires:lfs
   $TESTTMP/server/.hg/requires:lfs

tests/test-lfs-test-server.t

@@ -74,6 +74,7 b' store.'
   http auth: user foo, password ***
   pushing to ../repo2
   http auth: user foo, password ***
+  http auth: user foo, password ***
   query 1; heads
   searching for changes
   1 total queries in *s (glob)
@@ -209,6 +210,7 b' actions property completely.'
   http auth: user foo, password ***
   pushing to ../repo1
   http auth: user foo, password ***
+  http auth: user foo, password ***
   query 1; heads
   searching for changes
   all remote heads known locally
@@ -477,6 +479,7 b' Test a corrupted file upload'
   http auth: user foo, password ***
   pushing to ../repo1
   http auth: user foo, password ***
+  http auth: user foo, password ***
   query 1; heads
   searching for changes
   all remote heads known locally