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Mention the range of Python versions that need the workaround so we can remove it once Python 3.10 goes EOL.

Co-authored-by: Michael Howitz <icemac@gmx.net>

src/zope/publisher/browser.py

@@ -679,7 +679,7 @@ def __init__(self, aFieldStorage):
 
         if 'seekable' not in d and isinstance(
             file, tempfile.SpooledTemporaryFile
-        ):
+        ):  # Python 3.7 to 3.10
             # NB: can't assign file._file.seekable, file._file might roll over
             d['seekable'] = lambda: file._file.seekable()