Why am I getting permission denied on my Travis CI build for rebar?

I ran a build, on Travis CI and got a permission denied error:

$ source ${TRAVIS_HOME}/otp/23.0/activate 3.01s
$ ./rebar get-deps /home/travis/.travis/functions: line 355: ./rebar: Permission denied The command "eval ./rebar get-deps " failed.
Retrying, 2 of 3. /home/travis/.travis/functions: line 355: ./rebar: Permission denied The command "eval ./rebar get-deps " failed.
Retrying, 3 of 3. /home/travis/.travis/functions: line 355: ./rebar: Permission denied The command "eval ./rebar get-deps " failed 3 times.
The command “./rebar get-deps” failed and exited with 126 during .
Your build has been stopped.

I don’t understand why I am getting this error message. I used the .travis.yml from the nitrogen framework which my project uses as a base. As you can see my .travis.yml is the same. Can someone please explain why this is happening and how to fix it?