[PATCH] transplant: properly skip empty changeset (issue4423)

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at fb.com>
# Date 1420781772 28800
#      Thu Jan 08 21:36:12 2015 -0800
# Node ID 85766f010b8a1d93d13babc6f4dbb3d031eb4f84
# Parent  bb3ee61cfaa1d3f085c7577f48f566a0f31a6985
transplant: properly skip empty changeset (issue4423)

If resolving a merge conflict result in an empty changesets, we now properly
skip the changeset instead of crashing.

Original patch from Robert Collins <robertc at robertcollins.net>.

diff --git a/hgext/transplant.py b/hgext/transplant.py
--- a/hgext/transplant.py
+++ b/hgext/transplant.py
@@ -299,12 +299,16 @@ class transplanter(object):
 
     def resume(self, repo, source, opts):
         '''recover last transaction and apply remaining changesets'''
         if os.path.exists(os.path.join(self.path, 'journal')):
             n, node = self.recover(repo, source, opts)
-            self.ui.status(_('%s transplanted as %s\n') % (short(node),
-                                                           short(n)))
+            if n:
+                self.ui.status(_('%s transplanted as %s\n') % (short(node),
+                                                               short(n)))
+            else:
+                self.ui.status(_('%s skipped due to empty diff\n')
+                               % (short(node),))
         seriespath = os.path.join(self.path, 'series')
         if not os.path.exists(seriespath):
             self.transplants.write()
             return
         nodes, merges = self.readseries()
@@ -341,16 +345,20 @@ class transplanter(object):
                 raise util.Abort(
                     _('working dir not at transplant parent %s') %
                                  revlog.hex(parent))
             if merge:
                 repo.setparents(p1, parents[1])
-            n = repo.commit(message, user, date, extra=extra,
-                            editor=self.getcommiteditor())
-            if not n:
-                raise util.Abort(_('commit failed'))
-            if not merge:
-                self.transplants.set(n, node)
+            modified, added, removed, deleted = repo.status()[:4]
+            if merge or modified or added or removed or deleted:
+                n = repo.commit(message, user, date, extra=extra,
+                                editor=self.getcommiteditor())
+                if not n:
+                    raise util.Abort(_('commit failed'))
+                if not merge:
+                    self.transplants.set(n, node)
+            else:
+                n = None
             self.unlog()
 
             return n, node
         finally:
             wlock.release()
diff --git a/tests/test-transplant.t b/tests/test-transplant.t
--- a/tests/test-transplant.t
+++ b/tests/test-transplant.t
@@ -766,10 +766,26 @@ test transplanting a patch turning into 
   $ hg ci -Am addb2 b
   $ hg transplant -s ../binarysource 2
   searching for changes
   applying 7a7d57e15850
   skipping emptied changeset 7a7d57e15850
+
+Test empty result in --continue
+
+  $ hg transplant -s ../binarysource 1
+  searching for changes
+  applying 645035761929
+  file b already exists
+  1 out of 1 hunks FAILED -- saving rejects to file b.rej
+  patch failed to apply
+  abort: fix up the merge and run hg transplant --continue
+  [255]
+  $ hg status
+  ? b.rej
+  $ hg transplant --continue
+  645035761929 skipped due to empty diff
+
   $ cd ..
 
 Explicitly kill daemons to let the test exit on Windows
 
   $ "$TESTDIR/killdaemons.py" $DAEMON_PIDS