bookmarks: keep bookmarks in .hg/store if new config set Bookmarks storage consists of two parts: (1) the set of bookmarks and their positions, and (2) the current bookmark. The former can get updated by exchange, while the latter cannot. However, they are both stored in directly .hg/ and protected by repo.wlock(). As a result, ugly workarounds were needed. This patch introduces a new config option to store the set of bookmarks and their positions in .hg/store/ but still storing the current bookmark directory in .hg/. The config option only takes effect at repo creation time. It results in a new requirement being set. Differential Revision: https://phab.mercurial-scm.org/D6387