Fix undo after aborted commit bug

Commit would overwrite undo.dirstate unconditionally, so an undo after
an aborted commit would restore the dirstate from the aborted commit
and not the prior transaction.

This copies dirstate to journal.dirstate and moves it after a
successful transaction.

mercurial/hg.py

@@ -675,11 +675,15 b' class localrepository:'
             ds = self.opener("dirstate").read()
         except IOError:
             ds = ""
-        self.opener("undo.dirstate", "w").write(ds)
+        self.opener("journal.dirstate", "w").write(ds)
 
-        return transaction.transaction(self.ui.warn,
-                                       self.opener, self.join("journal"),
-                                       self.join("undo"))
+        def after():
+            util.rename(self.join("journal"), self.join("undo"))
+            util.rename(self.join("journal.dirstate"),
+                        self.join("undo.dirstate"))
+
+        return transaction.transaction(self.ui.warn, self.opener,
+                                       self.join("journal"), after)
 
     def recover(self):
         lock = self.lock()

mercurial/transaction.py

@@ -50,7 +50,7 b' class transaction:'
         self.file.close()
         self.entries = []
         if self.after:
-            util.rename(self.journal, self.after)
+            self.after()
         else:
             os.unlink(self.journal)
         self.journal = None

tests/test-hup.out

@@ -7,4 +7,4 b' rollback completed'
 00changelog.d
 00changelog.i
 data
-undo.dirstate
+journal.dirstate