!!for information !! - for those who install openproject from source
the version of the 2_2_2_backport2 est not 2_2_2 but 2_2_3 online
see
https://github.com/tessi/sprockets/blob/master/lib/sprockets/version.rb

so you can’t install it
i made a fork and install it after reverted it and a changed the reference in the Gemfile
https://github.com/lanfeust21/sprockets/blob/2_2_2_backport2/lib/sprockets/version.rb

but this version is really the 2_2_3 version resulting from the merge

best regards