diff -r de519517f597 -r 33d1b81c6ef0 mercurial/repair.py
--- a/mercurial/repair.py	Wed Jan 21 21:47:27 2015 +0100
+++ b/mercurial/repair.py	Wed Jan 21 15:54:52 2015 -0800
@@ -17,6 +17,12 @@
                   repo.ui.config('experimental', 'strip-bundle2-version'))
     if usebundle2:
         cgversion = repo.ui.config('experimental', 'strip-bundle2-version')
+        if cgversion not in changegroup.packermap:
+            repo.ui.warn(_('unknown strip-bundle2-version value %r; ' +
+                            'should be one of %r\n') %
+                         (cgversion, sorted(changegroup.packermap.keys()),))
+            cgversion = '01'
+            usebundle2 = False
     else:
         cgversion = '01'