I am on master and can't checkout using self check. When I enter a barcode I get the following error: Undefined subroutine &main::CanBookBeIssuedCheckout called at /home/nengard/kohaclone/opac/sco/sco-main.pl line 135. For help, please send mail to the webmaster (webmaster@debian), giving this error message and the time and date of the error.
Just tested in Koha 3.6.4 can't checkout there either.
I believe this is the same issue as Bug 7631, a patch for which has already passed QA. *** This bug has been marked as a duplicate of bug 7631 ***