Fully native mode: using HGitaly version with Blob/Tree methods

HGitaly 0.12.0dev1 was just pushed on PyPI and is the pivotal
version to stop skipping related RSpec tests of
spec/lib/gitlab/mercurial/hgitaly_blob_tree_spec.rb
11 jobs for !221 with topic/heptapod/fully-native in 21 minutes and 43 seconds (queued for 2 seconds)
latest merge request