localrepo: load the share source .hg/hgrc also in share-safe mode (API) The second part of the Share Safe Plan is to share source repo config also. This patch adds logic to load the source repo .hg/hgrc if we are in share safe mode. On unshare, we copy and prepend source config to current repo so that config which was shared is persisted. A test is added to show that now if we enable a hook on the source repo, that also runs on the shared repositories. API change as a new optional argument sharedvfs added to localrepo.loadhgrc() Differential Revision: https://phab.mercurial-scm.org/D8656