Let's say that there is a mention of JIRA issue in one of commit messages. Is it possible to pre-fill JIRA issue custom field when revision is created based on that? My initial attempt was to modify revision "summary" to include

Summary:
Here goes summary for fixing ST-5680

JIRA:
ST-5680

but since another block of JIRA: is added in the end automatically I get an error that there is a field duplicate.

Is there any way to mitigate that?