Heroku dyno dies after installing a buildpack

Heroku dyno dies after installing a buildpack

My rails app doesn't function properly when I install a new new buildpack.
When I run 'heroku ps', it shows that the dyno crashed.
Here are my Heroku logs:
/usr/local/lib/ruby/1.9.1/rubygems.rb:328:in bin_path': can't find gem
bundler (>= 0) (Gem::GemNotFoundException)
from <internal:gem_prelude>:199:inmethod_missing'
2013-09-14T17:54:40.029673+00:00 app[web.1]: from /app/bin/bundle:3:in `'
2013-09-14T17:54:41.382417+00:00 heroku[web.1]: Process exited with status 1
2013-09-14T17:54:41.393537+00:00 heroku[web.1]: State changed from
starting to crashed
My suspicion: I think the environment variables are being overwritten
after installing the buildpack. This is confirmed when I compared the
$PATH variable before and after installing the buildpack. I tried to set
the $PATH, $GEM_PATH manually (using config:set) but no success yet. I
doubt if there are some other variables which are being over written too.
The buildpack I'm trying to install is or heroku config:
BUILDPACK_URL: git://github.com/kannumehta/heroku-buildpack-tex.git
GEM_PATH: vendor/bundle/ruby/2.0.0:/app/vendor/bundle/ruby/2.0.0
PATH:/app/bin:/app/vendor/bundle/ruby/2.0.0/bin:/usr/local/bin:/usr/bin:/bin:/app/.texlive/bin/x86_64-linux:/usr/local/bin:/usr/bin:/bin
I checked that the stack is 'cedar', so that is not an issue. Can you
please help me track down the issue? I have been stuck on this issue for a
while now :( Thanks in advance!