rust-index: avoid some cloning in find_gca_candidates()
Instead of keeping the information whether the current revision is
poisoned on `current_seen`, we extract it as a boolean.
This also allows us to simplify the explanation of `seen[r].is_poisoned()`,
as the exceptional case where it is poisoned right after `r` has been
determined to be a solution does no longer exist.
# Declare macOS-specific requirements for generating
# the compiled (frozen) set of requirements in
# ./requirements-macos.txt.
# If run on Windows, it may be necessary to run dos2unix
# on the output file to replace any CRLF newlines with LF.
# TODO: dulwich, pygit2, and pytest-vcr are flagged as being
# incompatible with in-memory resources. Maybe there's a
# way to bundle just them externally.
docutils
#dulwich
# Needed by the release note tooling
fuzzywuzzy
keyring
#pygit2
pygments
# Needed by the phabricator tests
#pytest-vcr