heroku dosen't support ruby 2.1.1

[amitmtrn]

Delta compression using up to 4 threads.
Compressing objects: 100% (51/51), done.
Writing objects: 100% (104/104), 25.94 KiB | 0 bytes/s, done.
Total 104 (delta 43), reused 104 (delta 43)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> Ruby app detected
remote: -----> Compiling Ruby/Rack
remote:  !
remote:  !     An error occurred while installing Ruby ruby-2.1.1
remote:  !     For supported Ruby versions see https://devcenter.heroku.com/articles/ruby-support#supported-runtimes
remote:  !     Note: Only the most recent version of Ruby 2.1 is supported on Cedar-14
remote:  !     Command: 'set -o pipefail; curl --fail --retry 3 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/cedar-14/ruby-2.1.1.tgz -s -o - | tar zxf - ' failed unexpectedly:
remote:  !     
remote:  !     gzip: stdin: unexpected end of file
remote:  !     tar: Child returned status 1
remote:  !     tar: Error is not recoverable: exiting now
remote:  !
remote: 
remote:  !     Push rejected, failed to compile Ruby app
remote: 
remote: Verifying deploy....
remote: 
remote: !   Push rejected to afternoon-citadel-9202.
remote: 
To *****
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to '*****'

I change the version to 2.1.7 and for now it work fine..
please consider to change the version