This patch fixes a crash in the libxml2 bindings for Python 3.x
that 'itstool' stumbles upon when processing UTF-8 data:

  https://issues.guix.gnu.org/issue/37468

Patch by Jan Matejek
from <https://bugzilla.opensuse.org/show_bug.cgi?id=1065270>.

--- libxml2-2.9.5.orig/python/libxml.c
+++ libxml2-2.9.5/python/libxml.c
@@ -1620,6 +1620,7 @@ libxml_xmlErrorFuncHandler(ATTRIBUTE_UNU
     PyObject *message;
     PyObject *result;
     char str[1000];
+    unsigned char *ptr = (unsigned char *)str;
 
 #ifdef DEBUG_ERROR
     printf("libxml_xmlErrorFuncHandler(%p, %s, ...) called\n", ctx, msg);
@@ -1636,12 +1637,20 @@ libxml_xmlErrorFuncHandler(ATTRIBUTE_UNU
 	    str[999] = 0;
         va_end(ap);
 
+#if PY_MAJOR_VERSION >= 3
+        /* Ensure the error string doesn't start at UTF8 continuation. */
+        while (*ptr && (*ptr & 0xc0) == 0x80)
+            ptr++;
+#endif
+
         list = PyTuple_New(2);
         PyTuple_SetItem(list, 0, libxml_xmlPythonErrorFuncCtxt);
         Py_XINCREF(libxml_xmlPythonErrorFuncCtxt);
-        message = libxml_charPtrConstWrap(str);
+        message = libxml_charPtrConstWrap(ptr);
         PyTuple_SetItem(list, 1, message);
         result = PyEval_CallObject(libxml_xmlPythonErrorFuncHandler, list);
+        /* Forget any errors caused in the error handler. */
+        PyErr_Clear();
         Py_XDECREF(list);
         Py_XDECREF(result);
     }
9b9e893adcf03556e'>tree</a><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.15-arm.conf?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>commit</a><a href='/guix/diff/gnu/packages/aux-files/linux-libre/5.15-arm.conf?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/aux-files/linux-libre/5.15-arm.conf'>
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<div class='path'>path: <a href='/guix/log/?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>root</a>/<a href='/guix/log/gnu?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>gnu</a>/<a href='/guix/log/gnu/packages?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>packages</a>/<a href='/guix/log/gnu/packages/aux-files?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>aux-files</a>/<a href='/guix/log/gnu/packages/aux-files/linux-libre?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>linux-libre</a>/<a href='/guix/log/gnu/packages/aux-files/linux-libre/5.15-arm.conf?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e'>5.15-arm.conf</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/gnu/packages/aux-files/linux-libre/5.15-arm.conf?id=ac3f7bad6768283a6a9e3739b9e893adcf03556e&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-02-19 01:00:01 +0100'>2023-02-19</span></td><td><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.15-arm.conf?id=e701f67246680c81dd111cf7136b936bf7d8718b'>gnu: linux-libre: Consistently provide the drop_monitor module.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is needed by, e.g., &lt;https://github.com/nhorman/dropwatch&gt;.
Build it as a module everywhere for consistency.

* gnu/packages/aux-files/linux-libre/4.14-i686.conf:
Set CONFIG_NET_DROP_MONITOR=m.
* gnu/packages/aux-files/linux-libre/4.14-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/4.19-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/4.19-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.10-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.4-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-x86_64.conf: Likewise.

Reported by mirai in #guix.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-02-12 01:00:00 +0100'>2023-02-12</span></td><td><a href='/guix/commit/gnu/packages/aux-files/linux-libre/5.15-arm.conf?id=017f1779e937a85e525debdb89807592b35f55ea'>gnu: linux-libre: Disable unprivileged BPF by default.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/aux-files/linux-libre/5.15-arm.conf:
Set CONFIG_BPF_UNPRIV_DEFAULT_OFF=y.
* gnu/packages/aux-files/linux-libre/5.15-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/5.15-x86_64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-arm.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-arm64.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-i686.conf: Likewise.
* gnu/packages/aux-files/linux-libre/6.1-x86_64.conf: Likewise.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>