diff -r 4ea521b3c554 -r 055b3cbe6c57 mercurial/manifest.py
--- a/mercurial/manifest.py	Sun Apr 12 14:37:55 2015 -0700
+++ b/mercurial/manifest.py	Sun Apr 12 23:01:18 2015 -0700
@@ -448,10 +448,7 @@
         # Using _lazymanifest here is a little slower than plain old dicts
         self._files = {}
         self._flags = {}
-        for f, n, fl in _parse(text):
-            self[f] = n
-            if fl:
-                self.setflag(f, fl)
+        self.parse(text)
 
     def _subpath(self, path):
         return self._dir + path
@@ -740,6 +737,12 @@
         _diff(self, m2)
         return result
 
+    def parse(self, text):
+        for f, n, fl in _parse(text):
+            self[f] = n
+            if fl:
+                self.setflag(f, fl)
+
     def text(self, usemanifestv2=False):
         """Get the full data of this manifest as a bytestring."""
         flags = self.flags