Heroku can't install bundler

gistfile1.txt

remote: -----> Ruby app detected
remote:        Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/bundler-1.15.2.tgz -s -o - | tar zxf - ' failed on attempt 1 of 3.
remote:        Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/bundler-1.15.2.tgz -s -o - | tar zxf - ' failed on attempt 2 of 3.
remote:  !
remote:  !     Command: 'set -o pipefail; curl -L --fail --retry 5 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/bundler-1.15.2.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