http://rack.rubyforge.org/doc/files/SPEC.html is outdated and does not
cover the latest Ruby 1.9 compatibility spec changes. For example
SPEC.html says "The values of the header must respond to each", but as
far as I know this is no longer the case, and the latest spec requires
that the values of the header be Strings. It is then the
responsibility of the handler to split the strings in order to obtain
the possible multiple header values.
However,
http://github.com/rack/rack/tree/master has no SPEC file.
What happened to the spec?