Replace jsonschema with better error messages

pre_commit/five.py

@@ -5,14 +5,20 @@ PY3 = str is not bytes
 
 if PY2:  # pragma: no cover (PY2 only)
     text = unicode  # flake8: noqa
+    string_types = (text, bytes)
 
     def n(s):
         if isinstance(s, bytes):
             return s
         else:
             return s.encode('UTF-8')
+
+    exec("""def reraise(tp, value, tb=None):
+    raise tp, value, tb
+""")
 else:  # pragma: no cover (PY3 only)
     text = str
+    string_types = (text,)
 
     def n(s):
         if isinstance(s, text):
@@ -20,6 +26,13 @@ else:  # pragma: no cover (PY3 only)
         else:
             return s.decode('UTF-8')
 
+    def reraise(tp, value, tb=None):
+        if value is None:
+            value = tp()
+        if value.__traceback__ is not tb:
+            raise value.with_traceback(tb)
+        raise value
+
 
 def to_text(s):
     return s if isinstance(s, text) else s.decode('UTF-8')