I know about this decision and I tried all advices, that were described
-----> Ruby app detected
-----> Compiling Ruby/Rails
-----> Using Ruby version: ruby-2.0.0
-----> Installing dependencies using 1.5.2
New app detected loading default bundler cache
Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
Fetching gem metadata from https://rubygems.org/..........
Fetching additional metadata from https://rubygems.org/..
Could not find thread_safe-0.3.0 in any of the sources
1) tried fully uninstall thread_safe 2) install different versions - 0.2.0 and 0.3.1
But I couldn't deploy app to heroku
Any ideas?