Probing for hard link support in the pid locking code is redundant since
git-annex init already probes that. But, it didn't seem worth threading
that data through; the pid locking code runs at most once per git-annex
process, and only on unusual filesystems. Optimising a single hard link
and unlink isn't worth it.
This commit was sponsored by Francois Marier on Patreon.
