Merge branch 'ma/ts-cleanups' into maint

Assorted bugfixes and clean-ups.

* ma/ts-cleanups:
  ThreadSanitizer: add suppressions
  strbuf_setlen: don't write to strbuf_slopbuf
  pack-objects: take lock before accessing `remaining`
  convert: always initialize attr_action in convert_attrs

diff --cc builtin/pack-objects.c
Simple merge

diff --cc convert.c
Simple merge

diff --cc strbuf.h
Simple merge