Merge branch 'fix-plain-diffs' into 'master'

Remove the email patches link for merge commits

Rugged's `to_mbox` method doesn't work for merge commits, so don't display the option to download them as email patches.  This is part of the fix for #1878, and gitlab/gitlab_git!27 allows a plain diff to be generated for a merge commit.  Together these changes should prevent the 500 errors described in the issue.

cc @sytse

See merge request !1737

CHANGELOG

@@ -17,6 +17,7 @@ v 7.10.0 (unreleased)
   - extend the commit calendar to show the actual commits made on a date (Hannes Rosenögger)
   - Fix a link in the patch update guide
   - Add a service to support external wikis (Hannes Rosenögger)
+  - Omit the "email patches" link and fix plain diff view for merge commits
   - List new commits for newly pushed branch in activity view.
   - Add sidetiq gem dependency to match EE
   - Add changelog, license and contribution guide links to project sidebar.
@@ -24,6 +25,7 @@ v 7.10.0 (unreleased)
   - Fix alignment of navbar toggle button (Cody Mize)
   - Fix checkbox rendering for nested task lists
   - Identical look of selectboxes in UI
+  - Upgrade the gitlab_git gem to version 7.1.3
   - Move "Import existing repository by URL" option to button.
   - Improve error message when save profile has error.
   - Passing the name of pushed ref to CI service (requires GitLab CI 7.9+)

Gemfile

@@ -39,7 +39,7 @@ gem "browser"
 
 # Extracting information from a git repository
 # Provide access to Gitlab::Git library
-gem "gitlab_git", '~> 7.1.2'
+gem "gitlab_git", '~> 7.1.3'
 
 # Ruby/Rack Git Smart-HTTP Server Handler
 gem 'gitlab-grack', '~> 2.0.0.rc2', require: 'grack'

Gemfile.lock

@@ -212,7 +212,7 @@ GEM
       mime-types (~> 1.19)
     gitlab_emoji (0.1.0)
       gemojione (~> 2.0)
-    gitlab_git (7.1.2)
+    gitlab_git (7.1.3)
       activesupport (~> 4.0)
       charlock_holmes (~> 0.6)
       gitlab-linguist (~> 3.0)
@@ -703,7 +703,7 @@ DEPENDENCIES
   gitlab-grack (~> 2.0.0.rc2)
   gitlab-linguist (~> 3.0.1)
   gitlab_emoji (~> 0.1)
-  gitlab_git (~> 7.1.2)
+  gitlab_git (~> 7.1.3)
   gitlab_meta (= 7.0)
   gitlab_omniauth-ldap (= 1.2.1)
   gollum-lib (~> 4.0.2)

app/views/projects/commit/_commit_box.html.haml

@@ -10,6 +10,7 @@
         Download as
         %span.caret
       %ul.dropdown-menu
+        - unless @commit.parents.length > 1
           %li= link_to "Email Patches", namespace_project_commit_path(@project.namespace, @project, @commit, format: :patch)
         %li= link_to "Plain Diff",    namespace_project_commit_path(@project.namespace, @project, @commit, format: :diff)
     = link_to namespace_project_tree_path(@project.namespace, @project, @commit), class: "btn btn-primary btn-grouped" do