merge: introduce a preresolve function

merge: introduce a preresolve function

The section of code that writes out the version of the file cached in the merge
state should only be run at preresolve time. This is so that if the premerge
keeps around conflict markers, those don't get overwritten before the main
merge.

--- a/mercurial/commands.py	Sun Oct 11 18:37:54 2015 -0700
+++ b/mercurial/commands.py	Sun Oct 11 20:12:12 2015 -0700
@@ -5589,7 +5589,10 @@
                     # resolve file
                     ui.setconfig('ui', 'forcemerge', opts.get('tool', ''),
                                  'resolve')
-                    if ms.resolve(f, wctx):
+                    complete, r = ms.preresolve(f, wctx)
+                    if not complete:
+                        r = ms.resolve(f, wctx)
+                    if r:
                         ret = 1
                 finally:
                     ui.setconfig('ui', 'forcemerge', '', 'resolve')

--- a/mercurial/merge.py	Sun Oct 11 18:37:54 2015 -0700
+++ b/mercurial/merge.py	Sun Oct 11 20:12:12 2015 -0700
@@ -287,7 +287,7 @@
             if entry[0] == 'u':
                 yield f
 
-    def _resolve(self, dfile, wctx, labels=None):
+    def _resolve(self, preresolve, dfile, wctx, labels=None):
         """rerun merge process for file path `dfile`"""
         if self[dfile] == 'r':
             return True, 0
@@ -302,17 +302,19 @@
         fla = fca.flags()
         if 'x' in flags + flo + fla and 'l' not in flags + flo + fla:
             if fca.node() == nullid:
-                self._repo.ui.warn(_('warning: cannot merge flags for %s\n') %
-                                   afile)
+                if preresolve:
+                    self._repo.ui.warn(
+                        _('warning: cannot merge flags for %s\n') % afile)
             elif flags == fla:
                 flags = flo
-        # restore local
-        f = self._repo.vfs('merge/' + hash)
-        self._repo.wwrite(dfile, f.read(), flags)
-        f.close()
-        complete, r = filemerge.premerge(self._repo, self._local, lfile, fcd,
-                                         fco, fca, labels=labels)
-        if not complete:
+        if preresolve:
+            # restore local
+            f = self._repo.vfs('merge/' + hash)
+            self._repo.wwrite(dfile, f.read(), flags)
+            f.close()
+            complete, r = filemerge.premerge(self._repo, self._local, lfile,
+                                             fcd, fco, fca, labels=labels)
+        else:
             complete, r = filemerge.filemerge(self._repo, self._local, lfile,
                                               fcd, fco, fca, labels=labels)
         if r is None:
@@ -323,9 +325,12 @@
             self.mark(dfile, 'r')
         return complete, r
 
+    def preresolve(self, dfile, wctx, labels=None):
+        return self._resolve(True, dfile, wctx, labels=labels)
+
     def resolve(self, dfile, wctx, labels=None):
         """rerun merge process for file path `dfile`"""
-        return self._resolve(dfile, wctx, labels=labels)[1]
+        return self._resolve(False, dfile, wctx, labels=labels)[1]
 
 def _checkunknownfile(repo, wctx, mctx, f, f2=None):
     if f2 is None:
@@ -855,7 +860,9 @@
                              overwrite)
             continue
         audit(f)
-        r = ms.resolve(f, wctx, labels=labels)
+        complete, r = ms.preresolve(f, wctx, labels=labels)
+        if not complete:
+            r = ms.resolve(f, wctx, labels=labels)
         if r is not None and r > 0:
             unresolved += 1
         else: