gh-XXXXX: Fix email.quoprimime.decode() stray CR with eol='\r\n'

decoded[:-1] only strips one character, leaving a stray \r when eol
is two characters. Fix: decoded[:-len(eol)].

Author: stefanzetzsche

Lib/email/quoprimime.py

@@ -272,7 +272,7 @@ def decode(encoded, eol=NL):
                 decoded += eol
     # Special case if original string did not end with eol
     if encoded[-1] not in '\r\n' and decoded.endswith(eol):
-        decoded = decoded[:-1]
+        decoded = decoded[:-len(eol)]
     return decoded