Raise Error for diff_between/commit_between for non fork mr's in satellite

app/views/projects/merge_requests/update_branches.js.haml

 :plain
   $(".target_branch").html("#{escape_javascript(options_for_select(@target_branches))}");
   $(".target_branch").trigger("liszt:updated");
-  $(".mr_target_commit").html("");
\ No newline at end of file
+  $(".mr_target_commit").html("");
+  $(".target_branch").trigger("change");
\ No newline at end of file

lib/gitlab/satellite/merge_action.rb

@@ -74,9 +74,7 @@ module Gitlab
             #this method doesn't take default options
             diffs = merge_repo.diff(common_commit, "source/#{merge_request.source_branch}")
           else
-            common_commit = merge_repo.git.native(:merge_base, default_options, ["#{merge_request.target_branch}", "#{merge_request.source_branch}"]).strip
-            #this method doesn't take default options
-            diffs = merge_repo.diff(common_commit, "#{merge_request.source_branch}")
+            raise "Attempt to determine diffs between for a non forked merge request in satellite MergeRequest.id:[#{merge_request.id}]"
           end
           diffs = diffs.map { |diff| Gitlab::Git::Diff.new(diff) }
           return diffs
@@ -109,7 +107,7 @@ module Gitlab
           if (merge_request.for_fork?)
             commits = merge_repo.commits_between("origin/#{merge_request.target_branch}", "source/#{merge_request.source_branch}")
           else
-            commits = merge_repo.commits_between("#{merge_request.target_branch}", "#{merge_request.source_branch}")
+            raise "Attempt to determine commits between for a non forked merge request in satellite MergeRequest.id:[#{merge_request.id}]"
           end
           commits = commits.map { |commit| Gitlab::Git::Commit.new(commit, nil) }
           return commits

spec/lib/gitlab/satellite/merge_action_spec.rb

@@ -38,16 +38,14 @@ describe 'Gitlab::Satellite::MergeAction' do
     end
 
     context 'between branches' do
-      it 'should get proper commits between' do
+      it 'should raise exception -- not expected to be used by non forks' do
         merge_request.target_branch = @one_after_stable[0]
         merge_request.source_branch = @master[0]
-        commits = Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).commits_between
-        verify_commits(commits, @one_after_stable[1], @master[1])
+        expect {Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).commits_between}.to raise_error
 
         merge_request.target_branch = @wiki_branch[0]
         merge_request.source_branch = @master[0]
-        commits = Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).commits_between
-        verify_commits(commits, @wiki_branch[1], @master[1])
+        expect {Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).commits_between}.to raise_error
       end
     end
   end
@@ -104,13 +102,7 @@ describe 'Gitlab::Satellite::MergeAction' do
       it 'should get proper diffs' do
         merge_request.target_branch = @close_commit1[0]
         merge_request.source_branch = @master[0]
-        diffs = Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).diffs_between_satellite
-
-        merge_request.target_branch = @close_commit1[0]
-        merge_request.source_branch = @master[0]
-        diff = Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).diff_in_satellite
-
-        is_a_matching_diff(diff, diffs)
+        expect{Gitlab::Satellite::MergeAction.new(merge_request.author, merge_request).diffs_between_satellite}.to raise_error
       end
     end
   end