largefiles: fix 'hg status' abort after merge

If a largefile is introduced on the branch that is merged into the
working copy, then 'hg status' would abort with an error like:

   $ hg status
   abort: .hglf/foo@33fdd332ec64: not found in manifest!

The problem was that the largefiles status code only looked in the
first parent for the largefile. Largefiles are now always reported as
modified if they don't exist in the first parent -- this matches the
behavior of localrepo.status for normal files.

hgext/largefiles/reposetup.py

@@ -156,7 +156,11 b' def reposetup(ui, repo):'
                                 ignored, clean) = s
                         if parentworking:
                             for lfile in unsure:
-                                if ctx1[lfutil.standin(lfile)].data().strip() \
+                                standin = lfutil.standin(lfile)
+                                if standin not in ctx1:
+                                    # from second parent
+                                    modified.append(lfile)
+                                elif ctx1[standin].data().strip() \
                                         != lfutil.hashfile(self.wjoin(lfile)):
                                     modified.append(lfile)
                                 else:

tests/test-largefiles.t

@@ -645,6 +645,23 b' been very problematic).'
   $ cat sub2/large7
   large7
 
+Test status after merging with a branch that introduces a new largefile:
+
+  $ echo large > large
+  $ hg add --large large
+  $ hg commit -m 'add largefile'
+  $ hg update -q ".^"
+  $ echo change >> normal3
+  $ hg commit -m 'some change'
+  created new head
+  $ hg merge
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+  getting changed largefiles
+  1 largefiles updated, 0 removed
+  $ hg status
+  M large
+
 Test that a normal file and a largefile with the same name and path cannot
 coexist.