Error Pushing To Heroku, Rails3 beta4

i'm getting an error when pushing to heroku using rails 3 beta 4. i've managed to deploy before using it but for some reason i'm getting a strange error now. I'm on os x, snow leopard. I've been using rvm with both 1.9.2 preview and head, i also just reverted back to the system ruby 1.8.7 -p254 but they all give me the same error:

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git push heroku master 
Counting objects: 334, done. 
Delta compression using up to 2 threads. 
Compressing objects: 100% (285/285), done. 
Writing objects: 100% (310/310), 48.73 KiB, done. 
Total 310 (delta 119), reused 0 (delta 0) 
-----> Heroku receiving push 
-----> Rails app detected 
-----> Gemfile detected, running Bundler 
       Unresolved dependencies detected; Installing... 
......... 
......... 
INSTALLS/BUNDLES ALL THE GEMS AND EVERYTHING WORKS FINE UNTILL HERE: 
......... 
......... 
Your bundle is complete! Use `bundle show [gemname]` to see where a 
bundled gem is installed. 
 Locking environment 
       /usr/ruby1.8.7/lib/ruby/site_ruby/1.8/rubygems/package/ 
tar_input.rb:49:in `initialize': not in gzip format 
(Zlib::GzipFile::Error) 
        from /usr/ruby1.8.7/lib/ruby/site_ruby/1.8/rubygems/package/ 
tar_input.rb:49:in `new' 
......... 
......... 
MORE STACK TRACE HERE: 
......... 
......... 
error: hooks/pre-receive exited with error code 1 
To g...@heroku.com:hostelizer.git 
 ! [remote rejected] master -> master (pre-receive hook de开发者_运维知识库clined) 
error: failed to push some refs to '...@heroku.com:hostelizer.git' 
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Any ideas would be gr8 as i'm not a guru with ruby/rails. Cheers.