unionrepo: dynamically create repository type from base repository
This is basically the same thing we just did for bundlerepo except
for union repositories.
.. api::
``unionrepo.unionrepository()`` is no longer usable on its own.
To instantiate an instance, call ``unionrepo.instance()`` or
``unionrepo.makeunionrepository()``.
Differential Revision: https://phab.mercurial-scm.org/D4556
#require test-repo
$ cd $TESTDIR/../contrib/fuzz
#if clang-libfuzzer
$ make -s clean all
#endif
#if no-clang-libfuzzer clang-6.0
$ make -s clean all CC=clang-6.0 CXX=clang++-6.0
#endif
#if no-clang-libfuzzer no-clang-6.0
$ exit 80
#endif
Just run the fuzzers for five seconds each to verify it works at all.
$ ./bdiff -max_total_time 5
$ ./mpatch -max_total_time 5
$ ./xdiff -max_total_time 5