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'))
guix/refs/?id=fff67cc8a7233179cc5e6eacb9659e7e79134111'>refs</a><a class='active' href='/guix/log/scripts'>log</a><a href='/guix/tree/scripts?id=fff67cc8a7233179cc5e6eacb9659e7e79134111'>tree</a><a href='/guix/commit/scripts?id=fff67cc8a7233179cc5e6eacb9659e7e79134111'>commit</a><a href='/guix/diff/scripts?id=fff67cc8a7233179cc5e6eacb9659e7e79134111'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/scripts'>
<input type='hidden' name='id' value='fff67cc8a7233179cc5e6eacb9659e7e79134111'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=fff67cc8a7233179cc5e6eacb9659e7e79134111'>root</a>/<a href='/guix/log/scripts?id=fff67cc8a7233179cc5e6eacb9659e7e79134111'>scripts</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/scripts?id=fff67cc8a7233179cc5e6eacb9659e7e79134111&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-06-09 12:02:27 +0200'>2018-06-09</span></td><td><a href='/guix/commit/scripts?id=75e24d7b0e19ab2164aecb340e82d07d2b9714e7'>pull: Install the new Guix in a profile.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-01-28 23:14:55 +0100'>2018-01-28</span></td><td><a href='/guix/commit/scripts?id=63666a348af5ef5190cbe9611c40f2b9188b7967'>guix: Let Emacs detect “scripts/guix.in” appropriate mode.</a><span class='msg-avail'>...</span></td><td>Mathieu Lirzin</td></tr>
<tr><td><span title='2018-01-23 15:01:15 +0100'>2018-01-23</span></td><td><a href='/guix/commit/scripts?id=6f774d481839f87178c5895ac2d661e141f879b8'>guix: Refactor script.</a><span class='msg-avail'>...</span></td><td>Mathieu Lirzin</td></tr>
<tr><td><span title='2018-01-23 10:13:16 +0100'>2018-01-23</span></td><td><a href='/guix/commit/scripts?id=cba386c1295b7054df22dfb4662b1b92f668e2c0'>build: Expand ‘scripts/guix’ at Make time.</a><span class='msg-avail'>...</span></td><td>Mathieu Lirzin</td></tr>
<tr><td><span title='2017-03-20 23:26:18 +0100'>2017-03-20</span></td><td><a href='/guix/commit/scripts?id=9437fd7399425ed281e1bfc13240288ba9078caa'>build: Install .go files to $libdir/guile/X.Y.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2016-04-06 23:21:26 +0200'>2016-04-06</span></td><td><a href='/guix/commit/scripts?id=7cffaeb60473e25a7ef8c1a8cb36e1531191873a'>challenge: Really exit with non-zero upon hash mismatch.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>