JabRef version JabRef-3.3dev--snapshot--2016-04-12--master--f8bce59.jar on Linux Mint LMDE

Steps to reproduce:

1. Options -> Preferences
2. Select "Brazilian Portuguese"
3. Restart JabRef
   ==> English interface...
   (all other languages work as expected)

Log:

22:03:37.907 [AWT-EventQueue-0] WARN net.sf.jabref.logic.l10n.Localization - Could not find bundles for language pt_br, switching to full english language
java.util.MissingResourceException: Can't find bundle for base name l10n/JabRef, locale pt_br
at java.util.ResourceBundle.throwMissingResourceException(ResourceBundle.java:1564) ~[?:1.8.0_66]
at java.util.ResourceBundle.getBundleImpl(ResourceBundle.java:1387) ~[?:1.8.0_66]
at java.util.ResourceBundle.getBundle(ResourceBundle.java:890) ~[?:1.8.0_66]
at net.sf.jabref.logic.l10n.Localization.createResourceBundles(Localization.java:41) ~[JabRef-3.3dev--snapshot--2016-04-12--master--f8bce59.jar:?]
at net.sf.jabref.logic.l10n.Localization.setLanguage(Localization.java:32) ~[JabRef-3.3dev--snapshot--2016-04-12--master--f8bce59.jar:?]
at net.sf.jabref.JabRef.start(JabRef.java:84) ~[JabRef-3.3dev--snapshot--2016-04-12--master--f8bce59.jar:?]
at net.sf.jabref.JabRefMain.lambda$main$0(JabRefMain.java:10) ~[JabRef-3.3dev--snapshot--2016-04-12--master--f8bce59.jar:?]
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311) [?:1.8.0_66]
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756) [?:1.8.0_66]
at java.awt.EventQueue.access$500(EventQueue.java:97) [?:1.8.0_66]
at java.awt.EventQueue$3.run(EventQueue.java:709) [?:1.8.0_66]
at java.awt.EventQueue$3.run(EventQueue.java:703) [?:1.8.0_66]
at java.security.AccessController.doPrivileged(Native Method) ~[?:1.8.0_66]
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76) [?:1.8.0_66]
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726) [?:1.8.0_66]
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201) [?:1.8.0_66]
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116) [?:1.8.0_66]
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105) [?:1.8.0_66]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101) [?:1.8.0_66]
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93) [?:1.8.0_66]
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82) [?:1.8.0_66]
Caused by: java.lang.NullPointerException
at java.io.Reader.(Reader.java:78) ~[?:1.8.0_66]
at java.io.InputStreamReader.(InputStreamReader.java:113) ~[?:1.8.0_66]
at net.sf.jabref.logic.l10n.EncodingControl.newBundle(EncodingControl.java:51) ~[JabRef-3.3dev--snapshot--2016-04-12--master--f8bce59.jar:?]
at java.util.ResourceBundle.loadBundle(ResourceBundle.java:1501) ~[?:1.8.0_66]
at java.util.ResourceBundle.findBundle(ResourceBundle.java:1465) ~[?:1.8.0_66]
at java.util.ResourceBundle.getBundleImpl(ResourceBundle.java:1361) ~[?:1.8.0_66]
... 19 more