Issue #2202: Fix UnboundLocalError in AbstractDigestAuthHandler.get_algorithm_impls

Raise ValueError if algorithm is not MD5 or SHA.

Initial patch by Mathieu Dupuy.

diff --cc Lib/urllib/request.py
Simple merge

diff --cc Misc/NEWS
index 026db17c18e9663a0af349620c7b5c7ec62a12b9,9a775ac527cd684d5e62d6bc5c63c9e515465fbd..f7d12343855b54ce3584360d88f7fcb5a085df23
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -201,10 -90,10 +201,13 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #2202: Fix UnboundLocalError in
+   AbstractDigestAuthHandler.get_algorithm_impls.  Initial patch by Mathieu Dupuy.
+ 
 +- Issue #26167: Minimized overhead in copy.copy() and copy.deepcopy().
 +  Optimized copying and deepcopying bytearrays, NotImplemented, slices,
 +  short lists, tuples, dicts, sets.
 +
  - Issue #25718: Fixed pickling and copying the accumulate() iterator with
    total is None.