I use the JIRA issue id (e.g. ISPN-12345) as a prefix for all my task branches, and gco ISPN-12345_task fails:
Invalid argument: 'ISPN'
~/.config/fish/functions/gco.fish (line 46):
if [ $first -lt $last ]
^
in function '__gco' with arguments 'ISPN-12345_task'
called on line 75 of file ~/.config/fish/functions/gco.fish
in function 'gco' with arguments 'ISPN-12345_task'
Argument is not valid.