Fix check_is_enabled for recent systemd
Fix check_is_enabled for recent systemd

Recent systemd outputs extra BLACK_CIRCLE mark on list-dependencies like below.

```
% systemctl list-dependencies --plain sysinit.target                                                                                                                                                                                                                                                  [~/git]
sysinit.target
* dev-hugepages.mount
* dev-mqueue.mount
* kmod-static-nodes.service
* ldconfig.service
...
```

Not that the mark may vary depending on the locale.
http://cgit.freedesktop.org/systemd/systemd/tree/src/shared/util.c?id=v215#n5468

chinthakagodawita/specinfra,r7kamura/specinfra,nurse/specinfra,skamithi/specinfra,miketheman/specinfra,mizzy/specinfra,sergueik/specinfra,glenux/contrib-specinfra,winebarrel/specinfra,sean-horn/specinfra,hideyuki/specinfra,electrical/specinfra,pfaffle/specinfra,ihassin/specinfra,aibou/specinfra,seroron/specinfra,stefanhorning/specinfra,RoboticCheese/specinfra,tacahilo/specinfra,minimum2scp/specinfra,uroesch/specinfra,k0kubun/specinfra,verisign/specinfra,thenexus6/specinfra,gh2k/specinfra,edolnx/specinfra,optimizely/specinfra,elibus/specinfra,mactkg/specinfra,chef-partners/specinfra-cisco,lurdan/specinfra,serverspec/specinfra,stoned/specinfra,hfm/specinfra,sorah/specinfra,higanworks/specinfra,bodgit/specinfra,chorrell/specinfra