binascii: Prefer builtin unhexlify() implementation.

binascii/binascii.py

@@ -1,10 +1,11 @@
-from ubinascii import hexlify
+from ubinascii import *
 
-def unhexlify(data):
-    if len(data) % 2 != 0:
-        raise ValueError("Odd-length string")
+if not "unhexlify" in globals():
+    def unhexlify(data):
+        if len(data) % 2 != 0:
+            raise ValueError("Odd-length string")
 
-    return bytes([ int(data[i:i+2], 16) for i in range(0, len(data), 2) ])
+        return bytes([ int(data[i:i+2], 16) for i in range(0, len(data), 2) ])
 
 b2a_hex = hexlify
 a2b_hex = unhexlify