diff --git a/mercurial/context.py b/mercurial/context.py
--- a/mercurial/context.py
+++ b/mercurial/context.py
@@ -1824,7 +1824,7 @@
     def data(self, path):
         if self.isdirty(path):
             if self._cache[path]['exists']:
-                if self._cache[path]['data']:
+                if self._cache[path]['data'] is not None:
                     return self._cache[path]['data']
                 else:
                     # Must fallback here, too, because we only set flags.
diff --git a/tests/test-rebase-inmemory.t b/tests/test-rebase-inmemory.t
--- a/tests/test-rebase-inmemory.t
+++ b/tests/test-rebase-inmemory.t
@@ -797,5 +797,9 @@
   $ hg rebase -r . -d 1 --config ui.merge=internal:merge3
   rebasing 2:fb62b706688e "add b to foo" (tip)
   merging foo
-  abort: foo.orig@e780cf6f9041: not found in manifest!
-  [255]
+  hit merge conflicts; re-running rebase without in-memory merge
+  rebasing 2:fb62b706688e "add b to foo" (tip)
+  merging foo
+  warning: conflicts while merging foo! (edit, then use 'hg resolve --mark')
+  unresolved conflicts (see hg resolve, then hg rebase --continue)
+  [1]