Bundler: `Ref 'develop' was not found` for gkellogg/sxp-ruby

[anarchivist]

Using an up to date working copy on develop:

halfsour:rdf-vocab mark$ bundle
Fetching git://github.com/ruby-rdf/rdf.git
Fetching git://github.com/ruby-rdf/ld-patch.git
Fetching git://github.com/gkellogg/ebnf.git
Fetching git://github.com/ruby-rdf/json-ld.git
Fetching git://github.com/ruby-rdf/linkeddata.git
Fetching git://github.com/ruby-rdf/rdf-aggregate-repo.git
Fetching git://github.com/ruby-rdf/rdf-isomorphic.git
Fetching git://github.com/ruby-rdf/rdf-reasoner.git
Fetching git://github.com/ruby-rdf/rdf-spec.git
Fetching git://github.com/ruby-rdf/rdf-turtle.git
Fetching git://github.com/ruby-rdf/rdf-xsd.git
Fetching git://github.com/ruby-rdf/sparql.git
Fetching git://github.com/ruby-rdf/sparql-client.git
Fetching git://github.com/gkellogg/sxp-ruby.git
fatal: Needed a single revision
Git error: command `git rev-parse --verify develop` in directory
/Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/cache/bundler/git/sxp-ruby-c7af729dccecf34712927d706918e604d0981ee6
has failed.
Ref 'develop' was not found. Perhaps you mispelled it?
If this error persists you could try removing the cache directory
'/Users/mark/.rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/cache/bundler/git/sxp-ruby-c7af729dccecf34712927d706918e604d0981ee6'

[gkellogg]

The gem moved recently; I'll update this, and other Gemfiles to use the new reference.