Unfortunately, the shift to the Git version control caused my build of Robocode 188.8.131.52 to treat .sh and .command files used for Linux, Unix, Mac OS X etc. as files with Windows line endings. That is, these files contained the ^M character so Robocode and not be started up when running e.g. robocode.sh or robocode.command.
Hence I made a fast new release that fixes this. I am very sorry for the inconvenience this might have caused you.