The strop module and test_strop.py believe replace() with a 0 count

means "replace everything".  But the string module, string.replace()
amd test_string.py believe a 0 count means "replace nothing".
"Nothing" wins, strop loses.
Bugfix candidate.

Lib/test/test_strop.py

@@ -77,7 +77,7 @@ test('replace', 'one!two!three!', 'one@two!three!', '!', '@', 1)
 test('replace', 'one!two!three!', 'one@two@three!', '!', '@', 2)
 test('replace', 'one!two!three!', 'one@two@three@', '!', '@', 3)
 test('replace', 'one!two!three!', 'one@two@three@', '!', '@', 4)
-test('replace', 'one!two!three!', 'one@two@three@', '!', '@', 0)
+test('replace', 'one!two!three!', 'one!two!three!', '!', '@', 0)
 test('replace', 'one!two!three!', 'one@two@three@', '!', '@')
 test('replace', 'one!two!three!', 'one!two!three!', 'x', '@')
 test('replace', 'one!two!three!', 'one!two!three!', 'x', '@', 2)

Modules/stropmodule.c

@@ -1121,7 +1121,7 @@ strop_replace(PyObject *self, PyObject *args)
 {
 	char *str, *pat,*sub,*new_s;
 	int len,pat_len,sub_len,out_len;
-	int count = 0;
+	int count = -1;
 	PyObject *new;
 
 	if (!PyArg_ParseTuple(args, "t#t#t#|i:replace",