Shorten message and update changelog. Ref #1209.

CHANGES.rst

+v38.1.0
+-------
+
+* #1208: Improve error message when failing to locate scripts
+  in egg-info metadata.
+
 v38.0.0
 -------
 

pkg_resources/__init__.py

@@ -1514,8 +1514,9 @@ class NullProvider:
         script = 'scripts/' + script_name
         if not self.has_metadata(script):
             raise ResolutionError(
-                "No script named %r in 'scripts' directory of metadata "
-                "directory %r" % (script_name, self.egg_info))
+                "Script {script!r} not found in metadata at {self.egg_info!r}"
+                .format(**locals()),
+            )
         script_text = self.get_metadata(script).replace('\r\n', '\n')
         script_text = script_text.replace('\r', '\n')
         script_filename = self._fn(self.egg_info, script)