phabricator: don't abort if property writing fails during amending

Currently if one of the writediffproperty calls fails due to network issues
during the amending of commit messages to include the Diff. Rev. line, the
transaction is aborted and rolled back.  This means that the associations
between the commits and the DREVs are lost for any already amended commits
because the removal of the local tags isn't covered by the rollback.

Differential Revision: https://phab.mercurial-scm.org/D6835

hgext/phabricator.py

@@ -659,7 +659,12 b' def phabsend(ui, repo, *revs, **opts):'
 
                     mapping[old.node()] = [newnode]
                     # Update diff property
-                    writediffproperties(unfi[newnode], diffmap[old.node()])
+                    # If it fails just warn and keep going, otherwise the DREV
+                    # associations will be lost
+                    try:
+                        writediffproperties(unfi[newnode], diffmap[old.node()])
+                    except util.urlerr.urlerror:
+                        ui.warn(b'Failed to update metadata for D%s\n' % drevid)
                 # Remove local tags since it's no longer necessary
                 tagname = b'D%d' % drevid
                 if tagname in repo.tags():