I've added a simple way to pre-define a merge message template to be used while merging with the feature/hotfix/release commands.
You can use it by including the following in your .git/config:
message = Merge branch \\'$src_branch\\' into \\'$dst_branch\\'.
I've also fixed the usage of a local variable which was already defined but never used.
Add function to render pre-defined merge message.
Use rendered message (if available) while merging.
Make use of var defined a couple lines earlier.