pack_dirstate: in C version, for invalidation set dict to what we write to disk

For files written out in the last second, Mercurial used to invalidate all the
stat data (state, size, mode, mtime) while persisting to disk. This included
invalidating the data in the dirstate dict as well.

In commit 187bf2dde7c1, this was found to be unnecessary, and Mercurial
switched to invalidating only the mtime. However, in the C version of
pack_dirstate the value set in the dict was still the fully invalidated one.

Switch to invalidating just the mtime in the dict as well.

mercurial/parsers.c

@@ -261,7 +261,7 b' static PyObject *dirstate_unset;'
 static PyObject *pack_dirstate(PyObject *self, PyObject *args)
 {
 	PyObject *packobj = NULL;
-	PyObject *map, *copymap, *pl;
+	PyObject *map, *copymap, *pl, *mtime_unset = NULL;
 	Py_ssize_t nbytes, pos, l;
 	PyObject *k, *v, *pn;
 	char *p, *s;
@@ -342,9 +342,15 b' static PyObject *pack_dirstate(PyObject '
 		if (*s == 'n' && mtime == (uint32_t)now) {
 			/* See pure/parsers.py:pack_dirstate for why we do
 			 * this. */
-			if (PyDict_SetItem(map, k, dirstate_unset) == -1)
+			mtime = -1;
+			mtime_unset = Py_BuildValue(
+				"ciii", *s, mode, size, mtime);
+			if (!mtime_unset)
 				goto bail;
-			mtime = -1;
+			if (PyDict_SetItem(map, k, mtime_unset) == -1)
+				goto bail;
+			Py_DECREF(mtime_unset);
+			mtime_unset = NULL;
 		}
 		putbe32(mode, p);
 		putbe32(size, p + 4);
@@ -374,6 +380,7 b' static PyObject *pack_dirstate(PyObject '
 
 	return packobj;
 bail:
+	Py_XDECREF(mtime_unset);
 	Py_XDECREF(packobj);
 	return NULL;
 }