My Subscriptions title shows nullLiferay when subscribing to the home folder

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.0.X EE, 7.1.X, Master
• Component/s: Blogs, Documents & Media, Subscription Manager, ~ [Archived] Collaboration
• Labels: None
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Fix Priority: 4
• Sprint: Rhodochrosite 11/22-12/6
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/45274

Steps to reproduce:

1. Navigate to a public page and add the following portlets:
   • My Subscriptions
   • Documents and Media
   • Blogs
   • Bookmarks
2. On the Blogs portlet:
   • Click on the Subscribe link in the root/home folder
3. On the Documents and Media portlet:
   • Click on the info icon
   • Click on the star to subscribe to the root/home folder
4. On the Bookmarks portlet:
   • Click on the info icon
   • Click on the star to subscribe to the root/home folder
5. On the My Subscriptions portlet:
   • View that the Title showing for Blogs is nullLiferay
   • View that the Title showing for Documents and Media is nullLiferay
   • View that the Title showing for Bookmarks is Home

Expected result: Consistently show Home as title when the user is subscribed to the root/home folder
Actual result: Title shows nullLiferay for some portlets and Home for others

Reproduced on:
Tomcat 8.0.32 + MySQL 5.6. Portal master GIT ID: d07216a6c9794604b20eebf694da7f0c543f1985