Make parent sha links nicer for merge commits.

app/assets/stylesheets/sections/commits.scss

 .commit-head {
   @extend .well;
+  @extend .clearfix;
 
   padding: 14px;
   padding-bottom: 8px;
+  line-height: 24px;
 
   .browse-button {
     @extend .btn;
@@ -23,6 +25,10 @@
     margin-left: 10px
   }
 
+  &.merge-commit .sha-block {
+    clear: right;
+  }
+
   .committer {
     padding-left: 32px;
   }