tests: ignore inotify extension in test-duplicateoptions.py

The inotify extension is only available on linux and setup.py will not install
it on other platforms - but it will of course always be there in the source.

test-duplicateoptions.py tried to load most extensions (including inotify if
available). When the local uninstalled Mercurial was used it would thus always
load the inotify extension and cause a warning on unsupported platforms.

The inotify extension is not relevant for this test, so now we explicitly
ignore it.

tests/test-duplicateoptions.py

@@ -1,7 +1,7 b''
 import os
 from mercurial import ui, commands, extensions
 
-ignore = set(['highlight', 'win32text'])
+ignore = set(['highlight', 'inotify', 'win32text'])
 
 if os.name != 'nt':
     ignore.add('win32mbcs')