When there is a merge in git the comment mentions the branch name. Bamboo would then show it on its dashboard like this
If the branch name seems to follow a jira key pattern bamboo wrongly identifies it as a jira ticket, setting the underlink, trying to communicate with jira looking for details on this in-existing ticket, etc. In the case above bamboo would identify IB-12 as a jira ticket.
Bamboo should be able to let configure which strings patterns are not to be taken as jira tickets.