diff --git a/mercurial/repair.py b/mercurial/repair.py
--- a/mercurial/repair.py
+++ b/mercurial/repair.py
@@ -181,7 +181,8 @@ def strip(ui, repo, nodelist, backup=Tru
 
             for i in xrange(offset, len(tr.entries)):
                 file, troffset, ignore = tr.entries[i]
-                repo.svfs(file, 'a').truncate(troffset)
+                with repo.svfs(file, 'a', checkambig=True) as fp:
+                    fp.truncate(troffset)
                 if troffset == 0:
                     repo.store.markremoved(file)