Why won't bundler install the json 1.7.4 gem on OS X 10.8?
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I'm on OS X 10.8 with XCode 4.4, Ruby 1.9.3, and Rails 3.2.

When I clone my rails project from git and run:

    bundle install

I get:

Installing json (1.7.4) 
Errno::EPERM: Operation not permitted - /Users/myuser/.rvm/gems/ruby-1.9.3-p0/gems/json-1.7.4/.gitignore
An error occurred while installing json (1.7.4), and Bundler cannot continue.
Make sure that `gem install json -v '1.7.4'` succeeds before bundling.

Then I try:

    gem install json -v '1.7.4'

and get:

ERROR:  While executing gem ... (Errno::EPERM)
    Operation not permitted - /Users/scalessec/.rvm/gems/ruby-1.9.3-p0/gems/json-1.7.4/.gitignore

Okay. Permissions issue, right? Let's try:

    sudo gem install json -v '1.7.4'

No go. Here's what I get:

Building native extensions.  This could take a while...
ERROR:  Error installing json:
ERROR: Failed to build gem native extension.

/Users/myuser/.rvm/rubies/ruby-1.9.3-p0/bin/ruby extconf.rb
creating Makefile

make
compiling generator.c
make: /usr/bin/gcc-4.2: Permission denied
make: *** [generator.o] Error 1

What the heck?