TorPlugin: Authentication cookie did not match expected value

When working on #1267 (closed) restarted Briar several times to check Tor connections. In one of those times, the TorPlugin did not start with this trace:

06-25 16:05:18.114 W/PluginManagerImpl: Plugin org.briarproject.bramble.tor did not start
    org.briarproject.bramble.api.plugin.PluginException: net.freehaven.tor.control.TorControlError: Error reply: Authentication failed: Authentication cookie did not match expected value.
    org.briarproject.bramble.api.plugin.PluginException: net.freehaven.tor.control.TorControlError: Error reply: Authentication failed: Authentication cookie did not match expected value.
        at org.briarproject.bramble.plugin.tor.TorPlugin.start(TorPlugin.java:266)
        at org.briarproject.bramble.plugin.PluginManagerImpl$PluginStarter.run(PluginManagerImpl.java:213)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
        at java.lang.Thread.run(Thread.java:856)
     Caused by: net.freehaven.tor.control.TorControlError: Error reply: Authentication failed: Authentication cookie did not match expected value.
        at net.freehaven.tor.control.TorControlConnection.sendAndWaitForResponse(TorControlConnection.java:204)
        at net.freehaven.tor.control.TorControlConnection.authenticate(TorControlConnection.java:492)
        at org.briarproject.bramble.plugin.tor.TorPlugin.start(TorPlugin.java:251)
        at org.briarproject.bramble.plugin.PluginManagerImpl$PluginStarter.run(PluginManagerImpl.java:213) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569) 
        at java.lang.Thread.run(Thread.java:856)

Starting Briar again fixed it, but this should probably still not happen.