Fix str.rpartition(sep) when sep is not found in str.
Partially from SF patch #1551339, but also taken from head.
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 8908745..2ae3f61 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -6708,11 +6708,11 @@
}
PyDoc_STRVAR(rpartition__doc__,
-"S.rpartition(sep) -> (head, sep, tail)\n\
+"S.rpartition(sep) -> (tail, sep, head)\n\
\n\
Searches for the separator sep in S, starting at the end of S, and returns\n\
the part before it, the separator itself, and the part after it. If the\n\
-separator is not found, returns S and two empty strings.");
+separator is not found, returns two empty strings and S.");
static PyObject*
unicode_rpartition(PyUnicodeObject *self, PyObject *separator)