We have at least one instance (in two issues for the same change) of where the commit link added to an issue comment by the Skara bot is resulting in a 404 on Github.

https://bugs.openjdk.java.net/browse/JDK-8265463
https://bugs.openjdk.java.net/browse/JDK-8265464

The commit link is:

https://git.openjdk.java.net/jdk/commit/39907136

Adding one more digit from the hash makes it work:

https://git.openjdk.java.net/jdk/commit/399071369

My initial thought was that maybe there is a collision that is causing Github to behave like this, so I tried to manually cycle through 0-f as the final digit, but didn't get any hits. Should we add more digits to all generated commit links to try to mitigate this potential problem?