Issue #17220: two fixes for changeset 2528e4aea338.

First, because the mtime can exceed 4 bytes, make sure to mask it down to 4
bytes before getting its little-endian representation for writing out to a .pyc
file.

Two, cap an rsplit() call to 1 split, else can lead to too many values being
returned for unpacking.

Lib/importlib/_bootstrap.py

@@ -48,7 +48,7 @@ def _w_long(x):
     XXX Temporary until marshal's long functions are exposed.
 
     """
-    return int(x).to_bytes(4, 'little')
+    return (int(x) & 0xFFFFFFFF).to_bytes(4, 'little')
 
 
 # TODO: Expose from marshal
@@ -74,7 +74,7 @@ def _path_split(path):
         return front, tail
     for x in reversed(path):
         if x in path_separators:
-            front, tail = path.rsplit(x)
+            front, tail = path.rsplit(x, maxsplit=1)
             return front, tail
     return '', path