This userscript applies to forums.mozillazine.org.
It inserts titles to bug links that are plain URLs, in forums.mozillazine.org
i.e. instead of showing:
https://bugzilla.mozilla.org/show_bug.cgi?id=1147820 it shows: 1147820 - [meta] Improve Storage
It also converts links with titles like: Bug 1147820.
Note: the request for each link is done asynchronously, i.e. Firefox UI is not locked and frozen until the request completes.
v2.0: Script rewrite (based on johnp_'s contribution in the userscript 'Firefox for desktop - list fixed bugs in Mercurial'):
now the REST API is used (one (1) network connection is made for all unique examined bug IDs).
During this procedure, you may open the Web Console (Ctrl+Shift+K) to monitor progress. (screenshot)
v1.1 Now, a spinning icon appears at the end of each bug link during the title request procedure:
During the request : 
After appending title:
The script works and is tested on Tampermonkey and Violentmonkey.
Greasemonkey -any version- is not supported (the script might work, but is not tested).
If you have any bugs, bug fixes or ideas, please report at my GitHub repo