config.action_controller.perform_caching isn't used anymore in assets pipeline, instead we are using config.assets.digest now

Avoids double slash at start of paths when mounting an engine at the root.

AssetNotPrecompiledError should be raise when config.assets.digest = false, config.assets.compile = false and manifest file isn't present

not add more.!

Assets pipeline: fix in manifest location and remove unused code

Also:

- Refactor AssetDebuggingTest.
- Use the %r regexp syntax. That way we don't need to escape the /'s.

Add config.allow_debugging option to determine if the debug_assets query param can be passed by user

Fix CI and rename 1 misleading test case.

Rails 3.1 throws a Errno::ENOTDIR if files are put in assets directories

set a particular value for it. This allows servers to set it through
X-Sendfile-Type, read
https://github.com/rack/rack/blob/master/lib/rack/sendfile.rb for more
info. Anyways you can force this value in your production.rb

Otherwise, if bad data is cached in tmp/clear then the next invocation
of assets:precompile (or a regular incoming request) will pickup files from
tmp without regenerating them from source.

Otherwise, if bad data is cached in tmp/clear then the next invocation
of assets:precompile (or a regular incoming request) will pickup files from
tmp without regenerating them from source.

Rails 3.1 throws a Errno::ENOTDIR if files are put in assets directories

This reverts commit e3dbe66e.

Reason: Code changes are not allowed in docrails.