#require reporevlogstore A repo with unknown revlogv2 requirement string cannot be opened $ hg init invalidreq $ cd invalidreq $ echo exp-revlogv2.unknown >> .hg/requires $ hg log abort: repository requires features unknown to this Mercurial: exp-revlogv2.unknown! (see https://mercurial-scm.org/wiki/MissingRequirement for more information) [255] $ cd .. Can create and open repo with revlog v2 requirement $ cat >> $HGRCPATH << EOF > [experimental] > revlogv2 = enable-unstable-format-and-corrupt-my-data > EOF $ hg init empty-repo $ cd empty-repo $ cat .hg/requires dotencode exp-revlogv2.0 fncache store $ hg log Unknown flags to revlog are rejected >>> with open('.hg/store/00changelog.i', 'wb') as fh: ... fh.write(b'\x00\x04\xde\xad') and None $ hg log abort: unknown flags (0x04) in version 57005 revlog 00changelog.i! [255] $ cd .. Writing a simple revlog v2 works $ hg init simple $ cd simple $ touch foo $ hg -q commit -A -m initial $ hg log changeset: 0:96ee1d7354c4 tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: initial Header written as expected (changelog always disables generaldelta) $ f --hexdump --bytes 4 .hg/store/00changelog.i .hg/store/00changelog.i: 0000: 00 01 de ad |....| $ f --hexdump --bytes 4 .hg/store/data/foo.i .hg/store/data/foo.i: 0000: 00 03 de ad |....|