Merge pull request #2422 from rspec/switch-up-rspec-ci-version

Set RSpec version from env

Author: JonRowe

rspec-rails.gemspec

@@ -46,7 +46,7 @@ Gem::Specification.new do |s|
   # get released.
   %w[core expectations mocks support].each do |name|
     if ENV['RSPEC_CI']
-      s.add_runtime_dependency "rspec-#{name}", "= 4.0.0.pre"
+      s.add_runtime_dependency "rspec-#{name}", ENV.fetch('RSPEC_VERSION', '3.11.0.pre')
     elsif RSpec::Rails::Version::STRING =~ /pre/ # prerelease builds
       expected_rspec_version = "3.11.0.pre"
       s.add_runtime_dependency "rspec-#{name}", "= #{expected_rspec_version}"