Fix parser crash on parse error

Fixed #588.

Author: JukkaL

mypy/parse.py

@@ -1640,7 +1640,7 @@ def token_repr(tok: Token) -> str:
         return '"{}"'.format(tok.string)
     elif isinstance(tok, IntLit) or isinstance(tok, FloatLit) or isinstance(tok, ComplexLit):
         return 'numeric literal'
-    elif isinstance(tok, StrLit):
+    elif isinstance(tok, StrLit) or isinstance(tok, UnicodeLit):
         return 'string literal'
     elif (isinstance(tok, Punct) or isinstance(tok, Op)
           or isinstance(tok, Colon)):

mypy/test/data/parse-errors.test

@@ -402,3 +402,8 @@ from __future__ import *
 x = 1
 [out]
 file, line 1: Parse error before *
+
+[case testParseErrorBeforeUnicodeLiteral]
+x u'y'
+[out]
+file, line 1: Parse error before string literal