Reject blank environment vcariables in Gitlab::Git::RevList

Signed-off-by: Rémy Coutable <remy@rymai.me>

lib/gitlab/git/rev_list.rb

@@ -22,7 +22,7 @@ module Gitlab
 
       def valid?
         environment_variables.all? do |(name, value)|
-          value.start_with?(project.repository.path_to_repo)
+          value.to_s.start_with?(project.repository.path_to_repo)
         end
       end
 
@@ -35,7 +35,7 @@ module Gitlab
       end
 
       def environment_variables
-        @environment_variables ||= env.slice(*ALLOWED_VARIABLES)
+        @environment_variables ||= env.slice(*ALLOWED_VARIABLES).compact
       end
     end
   end

spec/lib/gitlab/git/rev_list_spec.rb

@@ -26,6 +26,13 @@ describe Gitlab::Git::RevList, lib: true do
 
           expect(rev_list).not_to be_valid
         end
+
+        it "ignores nil values" do
+          env = { var => nil }
+          rev_list = described_class.new('oldrev', 'newrev', project: project, env: env)
+
+          expect(rev_list).to be_valid
+        end
       end
     end
   end