escalation.belongs_to cache is broken

[bukzor]

The problem is that the cache is checked with the incoming string type, but the string type changes before the value is inserted:

A simple (but not elegant) fix:

--- hypothesis/internal/escalation.py
+++ hypothesis/internal/escalation.py
@@ -34,13 +34,14 @@ def belongs_to(package):
     cache = {text_type: {}, binary_type: {}}
 
     def accept(filepath):
+        ftype = type(filepath)
         try:
-            return cache[type(filepath)][filepath]
+            return cache[ftype][filepath]
         except KeyError:
             pass
         filepath = encoded_filepath(filepath)
         result = os.path.abspath(filepath).startswith(root)
-        cache[type(filepath)][filepath] = result
+        cache[ftype][filepath] = result
         return result
     accept.__name__ = 'is_%s_file' % (package.__name__,)
     return accept

[Zac-HD]

This looks a like a good fix to me - follow the contributing guide and make a pull!

[bukzor]

Do you want to see a regression test for this? If so, how would it work?