update the branch cache at the end of addchangegroup

This should avoid a bad performance problem when the branch cache is
not up-to-date, and hgweb can't write an updated version because it
lacks permissions.

mercurial/localrepo.py

@@ -1900,6 +1900,10 b' class localrepository(repo.repository):'
             del tr
 
         if changesets > 0:
+            # forcefully update the on-disk branch cache
+            self.ui.debug(_("updating the branch cache\n"))
+            self.branchcache = None
+            self.branchtags()
             self.hook("changegroup", node=hex(self.changelog.node(cor+1)),
                       source=srctype, url=url)
 

tests/test-acl.out

@@ -28,6 +28,7 b' adding foo/Bar/file.txt revisions'
 adding foo/file.txt revisions
 adding quux/file.py revisions
 added 3 changesets with 3 changes to 3 files
+updating the branch cache
 rolling back last transaction
 0:6675d58eff77
 
@@ -59,6 +60,7 b' calling hook pretxnchangegroup.acl: hgex'
 acl: acl.allow not enabled
 acl: acl.deny not enabled
 acl: changes have source "push" - skipping
+updating the branch cache
 rolling back last transaction
 0:6675d58eff77
 
@@ -94,6 +96,7 b' acl: acl.deny not enabled'
 acl: allowing changeset ef1ea85a6374
 acl: allowing changeset f9cafe1212c8
 acl: allowing changeset 911600dab2ae
+updating the branch cache
 rolling back last transaction
 0:6675d58eff77
 
@@ -383,6 +386,7 b' acl: acl.deny enabled, 0 entries for use'
 acl: allowing changeset ef1ea85a6374
 acl: allowing changeset f9cafe1212c8
 acl: allowing changeset 911600dab2ae
+updating the branch cache
 rolling back last transaction
 0:6675d58eff77
 
@@ -578,6 +582,7 b' acl: acl.deny enabled, 0 entries for use'
 acl: allowing changeset ef1ea85a6374
 acl: allowing changeset f9cafe1212c8
 acl: allowing changeset 911600dab2ae
+updating the branch cache
 rolling back last transaction
 0:6675d58eff77
 

tests/test-newbranch

@@ -41,6 +41,15 b' echo corrupted > .hg/branch.cache'
 hg log -qr foo
 cat .hg/branch.cache
 
+echo % push should update the branch cache
+hg init ../target
+echo % pushing just rev 0
+hg push -qr 0 ../target
+cat ../target/.hg/branch.cache
+echo % pushing everything
+hg push -qf ../target
+cat ../target/.hg/branch.cache
+
 echo % update with no arguments: tipmost revision of the current branch
 hg up -q -C 0
 hg up -q

tests/test-newbranch.out

@@ -83,6 +83,15 b' 4909a3732169c0c20011c4f4b8fdff4e3d89b23f'
 bf1bc2f45e834c75404d0ddab57d53beab56e2f8 default
 4909a3732169c0c20011c4f4b8fdff4e3d89b23f foo
 67ec16bde7f1575d523313b9bca000f6a6f12dca bar
+% push should update the branch cache
+% pushing just rev 0
+be8523e69bf892e25817fc97187516b3c0804ae4 0
+be8523e69bf892e25817fc97187516b3c0804ae4 default
+% pushing everything
+4909a3732169c0c20011c4f4b8fdff4e3d89b23f 4
+bf1bc2f45e834c75404d0ddab57d53beab56e2f8 default
+4909a3732169c0c20011c4f4b8fdff4e3d89b23f foo
+67ec16bde7f1575d523313b9bca000f6a6f12dca bar
 % update with no arguments: tipmost revision of the current branch
 bf1bc2f45e83
 4909a3732169 (foo) tip