bookmarks: make writing files out avoid ambiguity of file stat Cached attribute repo._bookmarks uses stat of '.hg/bookmarks' and '.hg/bookmarks.current' files to examine validity of cached contents. If writing these files out keeps ctime, mtime and size of them, change is overlooked, and old contents cached before change isn't invalidated as expected. To avoid ambiguity of file stat, this patch writes '.hg/bookmarks' and '.hg/bookmarks.current' files out with checkambig=True. This patch is a part of "Exact Cache Validation Plan": https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan