Fix clone URL losing selection after a single click in Safari and Chrome

Closes #9326

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 7.12.0 (unreleased)
+  - Fix clone URL losing selection after a single click in Safari and Chrome (Stan Hu)
   - Allow to configure location of the `.gitlab_shell_secret` file. (Jakub Jirutka)
   - Disabled expansion of top/bottom blobs for new file diffs
   - Update Asciidoctor gem to version 1.5.2. (Jakub Jirutka)

app/assets/javascripts/application.js.coffee

@@ -116,7 +116,10 @@ window.addEventListener "hashchange", shiftWindow
 
 $ ->
   # Click a .js-select-on-focus field, select the contents
-  $(".js-select-on-focus").on "focusin", -> $(this).select()
+  $(".js-select-on-focus").on "focusin", ->
+    # Prevent a mouseup event from deselecting the input
+    $(this).select().one 'mouseup', (e) ->
+      e.preventDefault()
 
   $('.remove-row').bind 'ajax:success', ->
     $(this).closest('li').fadeOut()