revlog: use raw content when building delta

Using external content provided by flagprocessor when building revlog delta
is wrong, because deltas are applied to raw contents in revlog.

This patch fixes the above issue by adding "raw=True".

test-revlog-raw.py now shows "local test passed", but there is more to fix.

mercurial/revlog.py

@@ -1635,7 +1635,7 b' class revlog(object):'
                         fh = ifh
                     else:
                         fh = dfh
-                    ptext = self.revision(rev, _df=fh)
+                    ptext = self.revision(rev, _df=fh, raw=True)
                     delta = mdiff.textdiff(ptext, t)
             header, data = self.compress(delta)
             deltalen = len(header) + len(data)

tests/test-revlog-raw.py.out

@@ -1,1 +1,2 b''
-abort: crashed: integrity check failed on _testrevlog.i:11
+local test passed
+abort: crashed: invalid patch