discovery: avoid wrong detection of multiple branch heads (issue6256)
This fix the code using obsolescence markers to remove "to be obsoleted" heads
during the detection of new head creation from push. The code turned out to not
use the branch information at all. This lead changeset from different branch to
be detected as new head on unrelated branch.
The code fix is actually quite simple. New tests have been added to covers
these cases.
Differential Revision: https://phab.mercurial-scm.org/D8259
How to add fuzzers (partially cribbed from oss-fuzz[0]):
1) git clone https://github.com/google/oss-fuzz
2) cd oss-fuzz
3) python infra/helper.py build_image mercurial
4) docker run --cap-add=SYS_PTRACE -it -v $HG_REPO_PATH:/hg-new \
gcr.io/oss-fuzz/mercurial bash
5) cd /src
6) rm -r mercurial
7) ln -s /hg-new mercurial
8) cd mercurial
9) compile
10) ls $OUT
Step 9 is literally running the command "compile", which is part of
the docker container. Once you have that working, you can build the
fuzzers like this (in the oss-fuzz repo):
python infra/helper.py build_fuzzers --sanitizer address mercurial $HG_REPO_PATH
(you can also say "memory", "undefined" or "coverage" for
sanitizer). Then run the built fuzzers like this:
python infra/helper.py run_fuzzer mercurial -- $FUZZER
0: https://github.com/google/oss-fuzz/blob/master/docs/new_project_guide.md