repoview: add an explicit set of all filter that show the wc parents
The `visible` set will always show the working copy parents. We record this in a
specific set. This will allow to fast path some access.
Differential Revision: https://phab.mercurial-scm.org/D7490
#require docutils gettext
$ $TESTDIR/check-gendoc de
checking for parse errors
Die Dateien werden dem Projektarchiv beim n\xc3\xa4chsten \xc3\x9cbernehmen (commit) hinzugef\xc3\xbcgt. Um dies vorher r\xc3\xbcckg\xc3\xa4ngig zu machen, siehe:hg:`forget`. (esc)
warning: please have a space before :hg: