gh-121735: Fix module-adjacent references in zip files (#123037)

* gh-116608: Apply style and compatibility changes from importlib_metadata.

* gh-121735: Ensure module-adjacent resources are loadable from a zipfile.

* gh-121735: Allow all modules to be processed by the ZipReader.

* Add blurb

* Remove update-zips script, unneeded.

* Remove unnecessary references to removed static fixtures.

* Remove zipdata fixtures, unused.

Author: jaraco

.gitattributes

@@ -27,8 +27,6 @@ Lib/test/cjkencodings/*                    noeol
 Lib/test/tokenizedata/coding20731.py       noeol
 Lib/test/decimaltestdata/*.decTest         noeol
 Lib/test/test_email/data/*.txt             noeol
-Lib/test/test_importlib/resources/data01/*           noeol
-Lib/test/test_importlib/resources/namespacedata01/*  noeol
 Lib/test/xmltestdata/*                     noeol
 
 # Shell scripts should have LF even on Windows because of Cygwin

Lib/importlib/resources/readers.py

@@ -34,8 +34,10 @@ def files(self):
 
 class ZipReader(abc.TraversableResources):
     def __init__(self, loader, module):
-        _, _, name = module.rpartition('.')
-        self.prefix = loader.prefix.replace('\\', '/') + name + '/'
+        self.prefix = loader.prefix.replace('\\', '/')
+        if loader.is_package(module):
+            _, _, name = module.rpartition('.')
+            self.prefix += name + '/'
         self.archive = loader.archive
 
     def open_resource(self, resource):