Repo url in build script

lib/build.rb

@@ -142,6 +142,7 @@ module GitlabCi
@process.environment['CI_BUILD_BEFORE_SHA'] = @before_sha
@process.environment['CI_BUILD_REF_NAME'] = @ref_name
@process.environment['CI_BUILD_ID'] = @id
+      @process.environment['CI_BUILD_REPO'] = @repo_url
@process.start