bundlerepo: use native str when peeking in __dict__
# skip-blame since it's just a string constant prefix
Differential Revision: https://phab.mercurial-scm.org/D1892
#require clang-libfuzzer test-repo $ cd $TESTDIR/../contrib/fuzz $ makeJust run the fuzzer for five seconds to verify it works at all. $ ./bdiff -max_total_time 5