Invert fix_unicode_literal to switch back to real literals.

maint/scripts/custom_fixers/fix_unicode_literal.py

@@ -1,18 +1,19 @@
-import re
-from lib2to3.pgen2 import token
 from lib2to3 import fixer_base
-from lib2to3.fixer_util import Name, Call
-
-_literal_re = re.compile(r"[uU][rR]?[\'\"]")
+from lib2to3.fixer_util import String
 
 
 class FixUnicodeLiteral(fixer_base.BaseFix):
     BM_compatible = True
-    PATTERN = """STRING"""
+    PATTERN = """
+    power< 'u'
+        trailer<
+            '('
+                arg=any
+            ')'
+        >
+    >
+    """
 
     def transform(self, node, results):
-        if node.type == token.STRING and _literal_re.match(node.value):
-            new = node.clone()
-            new.value = new.value[1:]
-            new.prefix = ''
-            node.replace(Call(Name(u'u', prefix=node.prefix), [new]))
+        arg = results["arg"]
+        node.replace(String('u'+arg.value, prefix=node.prefix))