resolve: restore .orig only after merge is fully complete (issue4952)

Previously, we'd restore the .orig file after the premerge is complete but
before the merge was complete. This would lead to the .orig file potentially
containing merge conflict markers in it, as a leftover from the last merge
attempt.

mercurial/commands.py

@@ -5670,10 +5670,10 b' def resolve(ui, repo, *pats, **opts):'
                     ui.setconfig('ui', 'forcemerge', '', 'resolve')
                     ms.commit()
 
-                # replace filemerge's .orig file with our resolve file
-                # for files in tocomplete, ms.resolve will not overwrite
-                # .orig -- only preresolve does
-                util.rename(a + ".resolve", a + ".orig")
+                # replace filemerge's .orig file with our resolve file, but only
+                # for merges that are complete
+                if complete:
+                    util.rename(a + ".resolve", a + ".orig")
 
         for f in tocomplete:
             try:
@@ -5687,6 +5687,10 b' def resolve(ui, repo, *pats, **opts):'
                 ui.setconfig('ui', 'forcemerge', '', 'resolve')
                 ms.commit()
 
+            # replace filemerge's .orig file with our resolve file
+            a = repo.wjoin(f)
+            util.rename(a + ".resolve", a + ".orig")
+
         ms.commit()
 
         if not didwork and pats:

tests/test-resolve.t

@@ -207,6 +207,30 b' resolve <file> should re-merge file'
   [1]
   $ grep '<<<' file1 > /dev/null
 
+test .orig behavior with resolve
+
+  $ echo resolve > file
+  $ hg resolve -q file1 --tool 'f --dump $TESTTMP/repo/file1.orig'
+  */file1~base*: (glob)
+  >>>
+  foo
+  <<<
+  */file1~other*: (glob)
+  >>>
+  foo
+  bar
+  <<<
+  $TESTTMP/repo/file1: (glob)
+  >>>
+  foo
+  baz
+  <<<
+  $TESTTMP/repo/file1.orig: (glob)
+  >>>
+  foo
+  baz
+  <<<
+
 resolve <file> should do nothing if 'file' was marked resolved
   $ echo resolved > file1
   $ hg resolve -m file1