branchcache: move head writing in a `_write_headers` method
Same rational: this will help having format variants.
# repoviewutil.py - constaints data relevant to repoview.py and other module
#
# Copyright 2012 Pierre-Yves David <pierre-yves.david@ens-lyon.org>
# Logilab SA <contact@logilab.fr>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
### Nearest subset relation
# Nearest subset of filter X is a filter Y so that:
# * Y is included in X,
# * X - Y is as small as possible.
# This create and ordering used for branchmap purpose.
# the ordering may be partial
subsettable = {
None: b'visible',
b'visible-hidden': b'visible',
b'visible': b'served',
b'served.hidden': b'served',
b'served': b'immutable',
b'immutable': b'base',
}