dirstate: make writing dirstate file out avoid ambiguity of file stat Cached attribute repo.dirstate uses stat of '.hg/dirstate' file to examine validity of cached contents. If writing '.hg/dirstate' file out keeps ctime, mtime and size of it, change is overlooked, and old contents cached before change isn't invalidated as expected. To avoid ambiguity of file stat, this patch writes '.hg/dirstate' file out with checkambig=True. The former diff hunk changes the code path for "dirstate.write()", and the latter changes the code path for "dirstate.savebackup()". This patch is a part of "Exact Cache Validation Plan": https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan