Fix a python_bytes_to_unicode issue, fixes #107

parso/utils.py

@@ -105,8 +105,17 @@ def python_bytes_to_unicode(source, encoding='utf-8', errors='strict'):
     if not isinstance(encoding, unicode):
         encoding = unicode(encoding, 'utf-8', 'replace')
 
-    # Cast to unicode
-    return unicode(source, encoding, errors)
+    try:
+        # Cast to unicode
+        return unicode(source, encoding, errors)
+    except LookupError:
+        if errors == 'replace':
+            # This is a weird case that can happen if the given encoding is not
+            # a valid encoding. This usually shouldn't happen with provided
+            # encodings, but can happen if somebody uses encoding declarations
+            # like `# coding: foo-8`.
+            return unicode(source, 'utf-8', errors)
+        raise
 
 
 def version_info():