push: fix bug in prepush logic and its tests

mercurial/localrepo.py

@@ -1575,9 +1575,8 b' class localrepository(repo.repository):'
                         localbrheads = self.branchmap()
                     else:
                         localbrheads = {}
-                        for n in heads:
-                            branch = self[n].branch()
-                            localbrheads.setdefault(branch, []).append(n)
+                        ctxgen = (self[n] for n in msng_cl)
+                        self._updatebranchcache(localbrheads, ctxgen)
 
                     newbranches = list(set(localbrheads) - set(remotebrheads))
                     if newbranches: # new branch requires --force

tests/test-push-warn

@@ -166,4 +166,32 b' hg -R k ci -m merge'
 hg -R k push -r a j
 echo
 
+echo % prepush -r should not allow you to sneak in new heads
+hg init l
+cd l
+echo a >> foo
+hg -q add foo
+hg -q branch a
+hg -q ci -d '0 0' -ma
+hg -q up null
+echo a >> foo
+hg -q add foo
+hg -q branch b
+hg -q ci -d '0 0' -mb
+cd ..
+hg -q clone l m -u a
+cd m
+hg -q merge b
+hg -q ci -d '0 0' -mmb
+hg -q up 0
+echo a >> foo
+hg -q ci -ma2
+hg -q up 2
+echo a >> foo
+hg -q branch -f b
+hg -q ci -d '0 0' -mb2
+hg -q merge 3
+hg -q ci -d '0 0' -mma
+hg push ../l -b b
+
 exit 0

tests/test-push-warn.out

@@ -100,7 +100,7 b' abort: push creates new remote branches:'
 1
 pushing to ../f
 searching for changes
-abort: push creates new remote branches: d!
+abort: push creates new remote branches: c, d!
 (use 'hg push -f' to force)
 1
 % fail on multiple head push
@@ -167,6 +167,11 b' 1 files updated, 0 files merged, 0 files'
 (branch merge, don't forget to commit)
 pushing to j
 searching for changes
+abort: push creates new remote branches: b!
+(use 'hg push -f' to force)
+
+% prepush -r should not allow you to sneak in new heads
+pushing to ../l
+searching for changes
 abort: push creates new remote heads on branch 'a'!
-(you should pull and merge or use push -f to force)
-
+(did you forget to merge? use push -f to force)