[PATCH stable] filectx: fix cmp() of file starting with '\1\n'

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1326213787 -32400
# Branch stable
# Node ID fc9a58eeb4a6d74768fe8a184638e2d247603d3c
# Parent  e4fc0f0b4f7e73f6cbfa132cf09b7027a909d08c
filectx: fix cmp() of file starting with '\1\n'

Because filelog.size() returns size+4 for data starting with '\1\n',
fctx.cmp(workingfcx) happens to return True wrongly. As the result,
`hg status` of a file starting with '\1\n' is always M, even if it isn't
modified.

Since there's no cheap way to fix bug of filelog.size() according to [1],
this patch works around the problem at filectx.cmp().

 [1]: http://markmail.org/message/5akdbmmqx7vq2fsg

diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -369,7 +369,10 @@ class filectx(object):
         returns True if different than fctx.
         """
         if (fctx._filerev is None and self._repo._encodefilterpats
-            or self.size() == fctx.size()):
+            or self.size() == fctx.size()
+            # filelog.size() may return size+4 if data startswith '\1\n'
+            or (isinstance(fctx, workingfilectx)
+                and self.size() - 4 == fctx.size())):
             return self._filelog.cmp(self._filenode, fctx.data())
 
         return True
diff --git a/tests/test-status.t b/tests/test-status.t
--- a/tests/test-status.t
+++ b/tests/test-status.t
@@ -272,3 +272,26 @@ hg status -A --change 1:
     modified
   R removed
   C deleted
+
+  $ cd ..
+
+hg status of binary file starting with '\1\n', a separator for metadata:
+
+  $ hg init repo5
+  $ cd repo5
+  $ printf '\1\nfoo' > 010a
+  $ hg ci -q -A -m 'initial checkin'
+  $ hg status -A
+  C 010a
+
+  $ printf '\1\nbar' > 010a
+  $ hg status -A
+  M 010a
+  $ hg ci -q -m 'modify 010a'
+  $ hg status -A --rev 0:1
+  M 010a
+
+  $ touch empty
+  $ hg ci -q -A -m 'add another file'
+  $ hg status -A --rev 1:2 010a
+  C 010a