I'm making this change so that I can construct response objects that
*don't* have the default headers applied. For example, I would like to
construct a response object from the return value of a controller.
If you need to construct a response object with the default headers,
then please use the alternate constructor:
`ActionDispatch::Response.create`
The bug caused a segfault and you can find more info about it at:
https://bugs.ruby-lang.org/issues/10685.
We did a couple of work arounds, but 2.2.1 rolled out and those aren't
needed anymore.
Here are the reverted commits:
- Revert "Work around for upstream Ruby bug #10685",
commit 707a433870.
- Revert "Fix segmentation fault in ActionPack tests",
commit 22e0a22d5f.
I'm also bumping the Ruby version check to 2.2.1 to prevent future
segfaults.
In f6e293ec54 we avoided a segfault in the
tests, however I think we should try to avoid the crash, as it may
happen in user code as well.
Here is what I distiled the bug down to:
```ruby
# Rails case - works on 2.0, 2.1; crashes on 2.2
require 'action_dispatch'
ActionDispatch::Response.new(200, "Content-Type" => "text/xml")
# General case - works on 2.0, 2.1; crashes on 2.2
def foo(optional = {}, default_argument: nil)
end
foo('quux' => 'bar')
```
Fixes regression in #18423. Merge default headers for new responses,
but don't merge when creating a response from the last session request.
hat tip @senny ❤️
