Merge branch 'capitalize-mentioned-issue-notes' into 'master'

Capitalize mentioned issue timeline notes

## What does this MR do?
Renames `mentioned in` to `Mentioned in` for issue timeline notes

## Are there points in the code the reviewer needs to double check?
Shouldn't be any  

## Why was this MR needed?
Resolves existing UI inconsistency as all the other issue timeline notes have their first letter capitalized.

## What are the relevant issue numbers?
Closes #21416 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-25_at_10.52.47_AM](/uploads/61de0a7d65fd739a6e565f6e63d2f52d/Screen_Shot_2016-08-25_at_10.52.47_AM.png)

After:
![Screen_Shot_2016-08-25_at_10.52.05_AM](/uploads/f67f353c285453306d6b80578b11e587/Screen_Shot_2016-08-25_at_10.52.05_AM.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !6028

CHANGELOG

@@ -27,6 +27,7 @@ v 8.12.0 (unreleased)
   - Change using size to use count and caching it for number of group members. !5935
   - Added 'only_allow_merge_if_build_succeeds' project setting in the API. !5930 (Duck)
   - Reduce number of database queries on builds tab
+  - Capitalize mentioned issue timeline notes (ClemMakesApps)
   - Use the default branch for displaying the project icon instead of master !5792 (Hannes Rosenögger)
   - Adds response mime type to transaction metric action when it's not HTML

app/services/system_note_service.rb

@@ -269,11 +269,11 @@ module SystemNoteService
   #
   # Example Note text:
   #
-  #   "mentioned in #1"
+  #   "Mentioned in #1"
   #
-  #   "mentioned in !2"
+  #   "Mentioned in !2"
   #
-  #   "mentioned in 54f7727c"
+  #   "Mentioned in 54f7727c"
   #
   # See cross_reference_note_content.
   #
@@ -308,7 +308,7 @@ module SystemNoteService
   # Check if a cross-reference is disallowed
   #
-  # This method prevents adding a "mentioned in !1" note on every single commit
+  # This method prevents adding a "Mentioned in !1" note on every single commit
   # in a merge request. Additionally, it prevents the creation of references to
   # external issues (which would fail).
   #
@@ -417,7 +417,7 @@ module SystemNoteService
   end
   def cross_reference_note_prefix
-    'mentioned in '
+    'Mentioned in '
   end
   def cross_reference_note_content(gfm_reference)

features/steps/shared/issuable.rb

@@ -179,7 +179,7 @@ module SharedIssuable
     project = Project.find_by(name: from_project_name)
     expect(page).to have_content(user_name)
-    expect(page).to have_content("mentioned in #{issuable.class.to_s.titleize.downcase} #{issuable.to_reference(project)}")
+    expect(page).to have_content("Mentioned in #{issuable.class.to_s.titleize.downcase} #{issuable.to_reference(project)}")
   end
   def expect_sidebar_content(content)

spec/features/issues/new_branch_button_spec.rb

@@ -20,7 +20,7 @@ feature 'Start new branch from an issue', feature: true do
     context "when there is a referenced merge request" do
       let(:note) do
         create(:note, :on_issue, :system, project: project,
-                                          note: "mentioned in !#{referenced_mr.iid}")
+                                          note: "Mentioned in !#{referenced_mr.iid}")
       end
       let(:referenced_mr) do
         create(:merge_request, :simple, source_project: project, target_project: project,

spec/features/notes_on_merge_requests_spec.rb

@@ -141,7 +141,7 @@ describe 'Comments', feature: true do
     let(:project2) { create(:project, :private) }
     let(:issue) { create(:issue, project: project2) }
     let(:merge_request) { create(:merge_request, source_project: project, source_branch: 'markdown') }
-    let!(:note) { create(:note_on_merge_request, :system, noteable: merge_request, project: project, note: "mentioned in #{issue.to_reference(project)}") }
+    let!(:note) { create(:note_on_merge_request, :system, noteable: merge_request, project: project, note: "Mentioned in #{issue.to_reference(project)}") }
     it 'shows the system note' do
       login_as :admin

spec/models/note_spec.rb

@@ -225,7 +225,7 @@ describe Note, models: true do
     let(:note) do
       create :note,
         noteable: ext_issue, project: ext_proj,
-        note: "mentioned in issue #{private_issue.to_reference(ext_proj)}",
+        note: "Mentioned in issue #{private_issue.to_reference(ext_proj)}",
         system: true
     end

spec/requests/api/notes_spec.rb

@@ -25,7 +25,7 @@ describe API::API, api: true  do
   let!(:cross_reference_note) do
     create :note,
     noteable: ext_issue, project: ext_proj,
-    note: "mentioned in issue #{private_issue.to_reference(ext_proj)}",
+    note: "Mentioned in issue #{private_issue.to_reference(ext_proj)}",
     system: true
   end

spec/services/system_note_service_spec.rb

@@ -330,13 +330,13 @@ describe SystemNoteService, services: true do
             let(:mentioner) { project2.repository.commit }
             it 'references the mentioning commit' do
-              expect(subject.note).to eq "mentioned in commit #{mentioner.to_reference(project)}"
+              expect(subject.note).to eq "Mentioned in commit #{mentioner.to_reference(project)}"
             end
           end
           context 'from non-Commit' do
             it 'references the mentioning object' do
-              expect(subject.note).to eq "mentioned in issue #{mentioner.to_reference(project)}"
+              expect(subject.note).to eq "Mentioned in issue #{mentioner.to_reference(project)}"
             end
           end
         end
@@ -346,13 +346,13 @@ describe SystemNoteService, services: true do
             let(:mentioner) { project.repository.commit }
             it 'references the mentioning commit' do
-              expect(subject.note).to eq "mentioned in commit #{mentioner.to_reference}"
+              expect(subject.note).to eq "Mentioned in commit #{mentioner.to_reference}"
             end
           end
           context 'from non-Commit' do
             it 'references the mentioning object' do
-              expect(subject.note).to eq "mentioned in issue #{mentioner.to_reference}"
+              expect(subject.note).to eq "Mentioned in issue #{mentioner.to_reference}"
             end
           end
         end
@@ -362,7 +362,7 @@ describe SystemNoteService, services: true do
   describe '.cross_reference?' do
     it 'is truthy when text begins with expected text' do
-      expect(described_class.cross_reference?('mentioned in something')).to be_truthy
+      expect(described_class.cross_reference?('Mentioned in something')).to be_truthy
     end
     it 'is falsey when text does not begin with expected text' do