Links to internal pages and attachments are changed to a self-referential link after changing the context path or protocol (http/https) in the base URL

This ticket is related to CONFSERVER-52060, but tracks a different set of symptoms.

• CONFSERVER-52060 tracks broken images, user mentions, and attachment macros. This set of symptoms have been fixed in Confluence 6.8.0
• CONFSERVER-55267 (this ticket) tracks broken internal page links and attachment links that specifically use the "shown as links" option. This set of symptoms are not yet fixed in Confluence 6.8.0.
• CONFSERVER-52441 tracks broken emoticons, which describes editing pages changes macro into hard links.

In local testing, this requires Collaborative Editing to be enabled to reproduce.

Steps to reproduce

1. Install Confluence without any context path. Version 6.8.0 was used in this test. Make sure Collaborative Editing is enabled.
2. Create a couple of test pages
3. On one of the pages, create a link to another page.
4. Drag an example attachment such as a zip file into the editor. Click it and choose to "Show as link"
5. Save the page
   Your page storage format should end up with something similar to:

   <p><ac:link><ri:page ri:content-title="another page" /></ac:link></p>
   <p><ac:link><ri:attachment ri:filename="myfile.zip" /></ac:link></p>
   

6. Shut down Confluence
7. Edit <confluence_install>/conf/server.xml and modify the context path, e.g. add "/confluence"
8. Start Confluence back up
9. Go to Confluence Admin > General Configurations, and update the base URL to reflect the new "/confluence" context path
10. Edit the page containing the link. (The editor might not load at first; try exiting the editor, refreshing the page, and edit again)
11. Without changing anything, save the page

Expected behavior

Nothing on the page changes

Actual behavior

The links to both the internal page and the attachment are now pointing to the edited page itself. The storage format for the link now looks like:

<p><ac:link /></p>
<p><ac:link /></p>

Additional notes

Customers have also reported that this can occur when changing Base URL protocol rather than context path, for example http to https.