Build fails if branch name is over 13 characters

I created a fork just to play around with creating my own custom becker boot disks and stumbled into this issue. I don't think it's just me, but if I create a branch with more than 13 characters in the name I get a build error. Specifically it is line 110 of $NITROSDIR/level1/dalpha/bootfiles/makefile. If I checkout main it builds without error. This is without changing any code at this point. My workaround is to change the line rules.mak to strip the branch name prefix, if there is one, then truncate to 13 characters if it is still too long.

diff --git a/rules.mak b/rules.mak
index 8e8e7187..0bc6a5d0 100644
--- a/rules.mak
+++ b/rules.mak
@@ -180,5 +180,5 @@ default: all
 buildinfo:
        @BUILDDATE="$$(git log -1 --format=%ad)"; \
        COMMITHASH="$$(git rev-parse --short HEAD)"; \
-       BRANCHNAME="$$(git branch --show-current)"; \
+       BRANCHNAME="$$(git branch --show-current | sed 's|.*/||' | cut -c1-13)"; \
        echo " fcc !$${BUILDDATE} ($${COMMITHASH} - $${BRANCHNAME})!" > "$(NITROS9DIR)/defs/buildinfo";

So my branch name hpmachining/custom-disks becomes just custom-disks for the purpose of the os9 padrom call in that makefile.