Taken from debian.

# Description: Disable update check by default.
Index: calibre/src/calibre/gui2/main.py
===================================================================
--- calibre.orig/src/calibre/gui2/main.py	2014-02-02 10:41:28.470954623 +0100
+++ calibre/src/calibre/gui2/main.py	2014-02-02 10:41:56.546954247 +0100
@@ -37,8 +37,8 @@
                       help=_('Start minimized to system tray.'))
     parser.add_option('-v', '--verbose', default=0, action='count',
                       help=_('Ignored, do not use. Present only for legacy reasons'))
-    parser.add_option('--no-update-check', default=False, action='store_true',
-            help=_('Do not check for updates'))
+    parser.add_option('--update-check', dest='no_update_check', default=True, action='store_false',
+            help=_('Check for updates'))
     parser.add_option('--ignore-plugins', default=False, action='store_true',
             help=_('Ignore custom plugins, useful if you installed a plugin'
                 ' that is preventing calibre from starting'))
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<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-04-09 02:42:54 +0000'>2020-04-09</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=91c231a2223440081426929828a23c7baa0214fd'>installer: Allow Alt+Shift toggle from non-Latin keyboard layouts.</a><span class='msg-avail'>...</span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2020-04-08 10:24:02 +0200'>2020-04-08</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=07a53bd512530d8f87e076263227216c467727bb'>installer: Turn help menu into parameters menu.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-04-06 15:06:03 +0200'>2020-04-06</span></td><td><a href='/guix/commit/gnu/installer/record.scm?id=786c9c39bc0826737e99f0c750ea30033cdbc202'>installer: Add a help page.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>