Problem reported upstream:
https://github.com/linsomniac/python-memcached/issues/176

---
 memcache.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/memcache.py b/memcache.py
index 05b6657..b935681 100644
--- a/memcache.py
+++ b/memcache.py
@@ -1300,8 +1300,8 @@ class Client(threading.local):
             key = key[1]
         if key is None:
             raise Client.MemcachedKeyNoneError("Key is None")
-        if key is '':
-            if key_extra_len is 0:
+        if key == '':
+            if key_extra_len == 0:
                 raise Client.MemcachedKeyNoneError("Key is empty")

             #  key is empty but there is some other component to key
--
2.26.2
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<div class='path'>path: <a href='/guix/log/?id=387b86ff003b051945ab08030169228556cc2a4a'>root</a>/<a href='/guix/log/gnu?id=387b86ff003b051945ab08030169228556cc2a4a'>gnu</a>/<a href='/guix/log/gnu/packages?id=387b86ff003b051945ab08030169228556cc2a4a'>packages</a>/<a href='/guix/log/gnu/packages/apparmor.scm?id=387b86ff003b051945ab08030169228556cc2a4a'>apparmor.scm</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/apparmor.scm?id=387b86ff003b051945ab08030169228556cc2a4a&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-12-04 23:08:20 +0100'>2022-12-04</span></td><td><a href='/guix/commit/gnu/packages/apparmor.scm?id=84424ae3c91c82c5d1b10728ba131b07d3acbb7a'>gnu: libapparmor: Restrict supported systems to GNU/Linux.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/apparmor.scm (libapparmor)[supported-systems]: New
field.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-12-04 23:08:20 +0100'>2022-12-04</span></td><td><a href='/guix/commit/gnu/packages/apparmor.scm?id=cbab7c1b3c0aa691bf407a7daf168ea790163dde'>gnu: Add pam-apparmor.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/apparmor.scm (pam-apparmor): New variable.

Co-authored-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Hilton Chain</td></tr>
<tr><td><span title='2022-12-04 23:08:20 +0100'>2022-12-04</span></td><td><a href='/guix/commit/gnu/packages/apparmor.scm?id=cb01e0a272cdeb5e4cf27c1f336ebae0550b02d3'>gnu: Add apparmor.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/apparmor.scm (apparmor): New variable.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Hilton Chain</td></tr>
<tr><td><span title='2022-12-04 23:08:20 +0100'>2022-12-04</span></td><td><a href='/guix/commit/gnu/packages/apparmor.scm?id=3a52318e60fa71b18b8473ca99e1e83d16c35d01'>gnu: Add libapparmor.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/apparmor.scm: New file.
(libapparmor): New variable.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add the file.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Hilton Chain</td></tr>