Since feedparser messes with Python’s internals by assigning
to __code__ it needs to import SGMLParseError too. It also
expects SGMLParseError, which was turned into AssertionError by
https://github.com/python/cpython/commit/e34bbfd61f405eef89e8aa50672b0b25022de320

--- feedparser-6.0.10/feedparser/sgml.py.orig	2023-03-18 09:24:50.976316932 +0100
+++ feedparser-6.0.10/feedparser/sgml.py	2023-03-18 09:26:32.971928811 +0100
@@ -28,6 +28,7 @@
 import re
 
 import sgmllib
+from sgmllib import SGMLParseError
 
 __all__ = [
     'sgmllib',
@@ -41,6 +42,7 @@
     'shorttagopen',
     'starttagopen',
     'endbracket',
+    'SGMLParseError',
 ]
 
 # sgmllib defines a number of module-level regular expressions that are
--- feedparser-6.0.10/feedparser/html.py.orig	2023-03-18 09:32:03.647114745 +0100
+++ feedparser-6.0.10/feedparser/html.py	2023-03-18 09:46:05.021142671 +0100
@@ -349,7 +349,7 @@
 
         try:
             return sgmllib.SGMLParser.parse_declaration(self, i)
-        except sgmllib.SGMLParseError:
+        except AssertionError:
             # Escape the doctype declaration and continue parsing.
             self.handle_data('<')
             return i+1
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<div class='path'>path: <a href='/guix/log/?id=3fbe449bd7e9b9422548beef61d24f6e5cb3b990'>root</a>/<a href='/guix/log/tests?id=3fbe449bd7e9b9422548beef61d24f6e5cb3b990'>tests</a>/<a href='/guix/log/tests/guix-git-authenticate.sh?id=3fbe449bd7e9b9422548beef61d24f6e5cb3b990'>guix-git-authenticate.sh</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/guix-git-authenticate.sh?id=3fbe449bd7e9b9422548beef61d24f6e5cb3b990&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-02-14 11:23:08 +0100'>2022-02-14</span></td><td><a href='/guix/commit/tests/guix-git-authenticate.sh?id=ca87601dd97dd9d356409827802eb0f8a3a535f0'>git-authenticate: Ensure the target is a descendant of the introductory commit.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes a bug whereby authentication of a commit *not* descending from the
introductory commit could succeed, provided the commit verifies the
authorization invariant.

In the example below, A is a common ancestor of the introductory commit
I and of commit X.  Authentication of X would succeed, even though it is
not a descendant of I, as long as X is authorized according to the
'.guix-authorizations' in A:

   X   	 I
    \   /
      A

This is because, 'authenticate-repository' would not check whether X
descends from I, and the call (commit-difference X I) would return X.

In practice that only affects forks because it means that ancestors of
the introductory commit already contain a '.guix-authorizations' file.

* guix/git-authenticate.scm (authenticate-repository): Add call to
'commit-descendant?'.
* tests/channels.scm ("authenticate-channel, not a descendant of introductory commit"):
New test.
* tests/git-authenticate.scm ("authenticate-repository, target not a descendant of intro"):
New test.
* tests/guix-git-authenticate.sh: Expect earlier test to fail since
9549f0283a78fe36f2d4ff2a04ef8ad6b0c02604 is not a descendant of
$intro_commit.  Add new test targeting an ancestor of the introductory
commit, and another test targeting the v1.2.0 commit.
* doc/guix.texi (Specifying Channel Authorizations): Add a sentence.
</span></span></td><td>Ludovic Courtès</td></tr>