index: avoid duplicating capacity-growth expression

We were duplicating the "*2" instead of reusing it. It's overflow-safe
to reuse as long as the growth factor (i.e. currently 2) is not larger
than sizeof(nodetreenode) (currently 64 or 128).

Differential Revision: https://phab.mercurial-scm.org/D4165

mercurial/cext/revlog.c

@@ -991,12 +991,11 b' static int nt_new(nodetree *self)'
 	if (self->length == self->capacity) {
 		unsigned newcapacity;
 		nodetreenode *newnodes;
-		if (self->capacity >= INT_MAX / (sizeof(nodetreenode) * 2)) {
-			PyErr_SetString(PyExc_MemoryError,
-					"overflow in nt_new");
+		newcapacity = self->capacity * 2;
+		if (newcapacity >= INT_MAX / sizeof(nodetreenode)) {
+			PyErr_SetString(PyExc_MemoryError, "overflow in nt_new");
 			return -1;
 		}
-		newcapacity = self->capacity * 2;
 		newnodes = realloc(self->nodes, newcapacity * sizeof(nodetreenode));
 		if (newnodes == NULL) {
 			PyErr_SetString(PyExc_MemoryError, "out of memory");