The check for a running ImageJ instance can block indefinitely.

I had a corrupt "/tmp/ImageJ-username-_0-012345.stub" which cause imagej to block indefinitely. The issue happens at line [127 of OtherInstance.java](https://github.com/imagej/imagej1/blob/master/ij/OtherInstance.java#L127)

ImageJInstance instance = (ImageJInstance) new ObjectInputStream(in).readObject();

That method wasn't returning. It's pretty rare, but somewhat obscure when it happens. I had to delete the tmp file and then I could run imagej from the cmd line again.

Start in ij/OtherInstance.java at line 127, where the ImageJInstance is read from the temporary stub stream. Reproduce the case with a corrupt /tmp/ImageJ-username-_0-012345.stub and trace why the read does not return. Done means a corrupt stub no longer blocks indefinitely and ImageJ can be launched from the command line.

Written by the indexing model from the issue text.