narrow: move from ELLIPSIS_NODE_FLAG to revlog.REVIDX_ELLIPSIS
We should have been using this value all along. Sigh.
Differential Revision: https://phab.mercurial-scm.org/D2008
narrowrepo: make repo requirement include the string 'experimental'
We can just move to "narrow" or similar when we finalize the
format. I'm not sure what the migration process from one requirement
to another should look like, but we're about to cross that bridge at
Google once this change lands, so hopefully we'll know soon.
Differential Revision: https://phab.mercurial-scm.org/D2007