sparse: take lock before writing requirements with `share-safe`, we will also write file in the store. So we take the `lock` before altering the requirements. Differential Revision: https://phab.mercurial-scm.org/D11993

largefiles: take lock before writing requirements With `share-safe`, we will also write file in the store. We now take the `lock` as needed. Differential Revision: https://phab.mercurial-scm.org/D11992

lfs: take lock before writing requirements With `share-safe`, we will also write file in the store, so we take the store lock before writing requirements. Differential Revision: https://phab.mercurial-scm.org/D11991

test: simpler requirements matching in test-repo-compengines.t We focus on the requirements relevant for this tests. Differential Revision: https://phab.mercurial-scm.org/D11990

test: simpler requirements matching in test-lfs-largefiles.t We focus on the requirements relevant for this tests. Differential Revision: https://phab.mercurial-scm.org/D11989

test: simpler requirements matching in test-sidedata.t We focus on the requirements relevant for this tests. Differential Revision: https://phab.mercurial-scm.org/D11988

test: simpler requirement matching in test-revlog-v2.t We narrow the matching toward the one we actually care about. Differential Revision: https://phab.mercurial-scm.org/D11987

test-copies: narrow the format check in test-copies-in-changeset.t This will reduce the noise when touching unrelated format variants. Differential Revision: https://phab.mercurial-scm.org/D11986

tests: use debugrequires instead of grepping the file directly With `share-safe`, the requirements are stored in multiple files so it seems better to use the command that retrieve the information wherever it is. Differential Revision: https://phab.mercurial-scm.org/D11985

tests: use debugrequires in test-upgrade-repo.t Whenever possible, we use the `hg debugrequires` command instead of directly grepping the file. Differential Revision: https://phab.mercurial-scm.org/D11984