context: cache self._status correctly at workingctx.status Before this patch, "workingctx.status" always replaces "self._status" by the recent result, even though: - status isn't calculated against the parent of the working directory, or - specified "match" isn't "always" one (status is only visible partially) If "workingctx" object is shared between some procedures indirectly referring "ctx._status", this incorrect caching may cause unexpected result: for example, "ctx._status" is used via "manifest()", "files()" and so on. To cache "self._status" correctly at "workingctx.status", this patch overwrites "self._status" in "workingctx._buildstatus" only when: - status is calculated against the parent of the working directory, and - specified "match" is "always" one This patch can be applied (and effective) only on default branch, because procedure around "basectx.status" is much different between stable and default: for example, overwriting "self._status" itself is executed not in "workingctx._buildstatus" but in "workingctx._poststatus", on stable branch.