tests/test-bad-extension.out

Fix confusing message from hg revert (issue332)

   % mkdir sub1
   % touch sub1/file1
   % hg add sub1/
   adding sub1/file1
   % hg rev sub1
   sub1: No such file in rev e4c586763258
   forgetting sub1/file1

*** failed to import extension badext: invalid syntax (badext.py, line 1)
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