Issue with pygit2's Conflict Iterator on SUSE SL-16.0

[thackara]

hello, we have noticed a problem with pygit2's Conflict Iterator with SUSE SL-16.0 linux:
ref: https://build.opensuse.org/public/build/devel:languages:python/16.0/x86_64/python-pygit2/_log

The test_add_conflict test fails:

[ 24s] ______________________________ test_add_conflict _______________________________
[ 24s]

[ 24s] conflict_ancestor, conflict_ours, conflict_theirs = index.conflicts['conflict.txt']
[ 24s] > assert conflict_ancestor.id == ancestor_blob_id
[ 24s] E AttributeError: 'NoneType' object has no attribute 'id'
[ 24s]
[ 24s] test/test_index.py:335: AttributeError

# our comparion logs with libgit2(1.9.1) and pygit2(1.18.2)
#### on 16.0

# with libgit2: git_index_conflict_add(index, &ancestor_entry, &ours_entry, NULL) -> git_index_conflict_get -> git_index_conflict_next
# __getitem__ : git_index_conflict_get
# CI.__next__: Conflict Iterator


abuild@sodium:/tmp/testrepo.git> /tmp/test_libgit2_conflict
DBG1: __getitem__ raw pointers: ancestor=0x565538872c80 INFO: Ancestor entry found. OID: fe858dce6bd7636ebb180dfaab9a2e6414456f3a
DBG2: __getitem__ raw pointers: ours=0x565538872c10 INFO: Ours entry found. OID: 424860eef4edb9f5a2dacbbd6dc8c2d2e7645035
DBG3: conflict_iter=0x565538872fa0
DBG4: CI.__next__ raw pointers: ancestor=0x565538872c80 ours=0x565538872c10 theirs=(nil)
DBG5: CI.__next__ entry: Ancestor: path=conflict.txt, mode=33261
DBG6: CI.__next__ entry: Ours: path=conflict.txt, mode=33188
DBG7: CI.__next__ entry: Theirs: None
abuild@sodium:/tmp/testrepo.git>


# with pygit2: index.add_conflict(ancestor, ours, None) -> index.conflicts.get -> [iter]index.conflicts
# CC: Conflict Collector
# CI: Conflict Iterator

abuild@sodium:/tmp/testrepo.git> python3 /tmp/test_pygit2_conflict.py
DBG1: before: centry_ancestor=<cdata 'void *' NULL>, centry_ours=<cdata 'void *' NULL>, centry_theirs=<cdata 'void *' NULL>
DBG2: after_to_c: centry_ancestor=<cdata 'struct git_index_entry *' owning 72 bytes>, centry_ours=<cdata 'struct git_index_entry *' owning 72 bytes>, centry_theirs=<cdata 'void *' NULL>
DBG3: conflict_add_err=0
DBG4: CC.__getitem__ raw pointers: ancestor=<cdata 'struct git_index_entry *' NULL> ours=<cdata 'struct git_index_entry *' 0x559b17f8f130> theirs=<cdata 'struct git_index_entry *' NULL>
DBG5: CC.__getitem__ python objects: ancestor=None ours=<path=conflict.txt id=424860eef4edb9f5a2dacbbd6dc8c2d2e7645035 mode=33188> theirs=None
Ancestor entry NOT found.
Ours entry found. OID: 424860eef4edb9f5a2dacbbd6dc8c2d2e7645035
DBG6: CI.__next__ raw pointers: ancestor=<cdata 'struct git_index_entry *' 0x559b18204070> ours=<cdata 'struct git_index_entry *' NULL> theirs=<cdata 'struct git_index_entry *' NULL>
DBG7: CI.__next__ python objects: ancestor=<path=EEEEEEEEEEEEEEEE id=fe858dce6bd7636ebb180dfaab9a2e6414456f3a mode=33261> ours=None theirs=None
(<pygit2.index.IndexEntry path=EEEEEEEEEEEEEEEE id=fe858dce6bd7636ebb180dfaab9a2e6414456f3a mode=33261>, None, None)
DBG6: CI.__next__ raw pointers: ancestor=<cdata 'struct git_index_entry *' NULL> ours=<cdata 'struct git_index_entry *' 0x559b17f8f130> theirs=<cdata 'struct git_index_entry *' NULL>
DBG7: CI.__next__ python objects: ancestor=None ours=<path=conflict.txt id=424860eef4edb9f5a2dacbbd6dc8c2d2e7645035 mode=33188> theirs=None
(None, <pygit2.index.IndexEntry path=conflict.txt id=424860eef4edb9f5a2dacbbd6dc8c2d2e7645035 mode=33188>, None)
abuild@sodium:/tmp/testrepo.git>

-> the ConflictItertaor behaviour seems to be fine with openSUSE:Factory and openSUSE:Tumbleweed versions.

ancestor reference appears 'poisoned' (ancestor->path: EEEEEEEEEEEEEEEE)

it is possible the build enviornment enabled some memory sanitization, could you investigate this from the pygit2 aspect?

cc: @hramrach