context: avoid breaking already fixed self._status at ctx.status() Before this patch, "status()" on "workingcommitctx" with "always match" object causes breaking "self._status" in "workingctx._buildstatus()", because "workingctx._buildstatus()" caches the result of "dirstate.status()" into "self._status" for efficiency, even though it should be fixed at construction for committing. For example, template function "diff()" without any patterns in "committemplate" implies "status()" on "workingcommitctx" with "always match" object, via "basectx.diff()" and "patch.diff()". Then, broken "self._status" causes committing unexpected files. To avoid breaking already fixed "self._status" at "ctx.status()", this patch overrides "_buildstatus" in "workingcommitctx". This patch doesn't write out the result of template function "diff()" in "committemplate" in "test-commit.t", because matching against files to be committed still has an issue fixed in subsequent patch.