2-3-stable on Ruby 1.8.8 regression

Symptom: can't convert Hash into String

Reproduction instructions:

rails depot

Caused by this commit:

http://github.com/rails/rails/commit/0200e20f148c96afceeebc4da7b598...

Stack traceback:

  /home/rubys/git/rails/railties/bin/../lib/rails_generator/base.rb:156:in `join'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/base.rb:156:in `destination_path'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/commands.rb:219:in `file'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/commands.rb:298:in `template'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/manifest.rb:47:in `send'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/manifest.rb:47:in `send_actions'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/manifest.rb:46:in `each'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/manifest.rb:46:in `send_actions'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/manifest.rb:31:in `replay'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/commands.rb:42:in `invoke!'
  /home/rubys/git/rails/railties/bin/../lib/rails_generator/scripts/../scripts.rb:31:in `run'
  /home/rubys/git/rails/railties/bin/rails:18

Value of relative_destination at the time of the error: {:assigns=>{:app_secret=>"c32e635d6a99c4458953f3e8dec469132a9bf5ea2fc5932688e5b41bfcb40da4457729c086ef58c7f7acfc655932118331294a04a08ea5732c938a8da115f6f2"}}

Note: this only occurs on 1.8.8, and does not affect Rails 3.0.