This isn’t really a Request Tracker bug, and already sent email to email@example.com.
In short, Plack::Handler::Starlet-0.24 (22-Apr-2014) won’t install correctly because it won’t pass test #8 (t/08chunked_req.t) because the test is hard-coded to use the file baybridge.jpg provided by its parent Plack package. The file baybridge.jpg was changed between Plack-1.0034 (02-Feb-2015, 79838b) and Plack-1.0036 (03-Jun-2015, 14750b) , so obviously the hard-coded test in Plack::Handler::Starlet also fails.
You can just --force the install of Plack::Handler::Starlet anyway (assuming all other tests are valid), or back down to Plack-1.0034, or you can temporarily change out the baybridge.jpg file in Plack-1.0036 with the one provided in Plack-1.0034. At least these options worked for me, there may be a better/more official way to handle this.