pkg/poudriere: dangling symlink to pkg.pkg.sig

For the last few days, approximately corresponding to when the pkg port 
upgraded to 1.17.0, the poudriere build process has been creating a 
dangling symlink from pkg.txz.sig to pkg.pkg.sig. Posting an issue to 
github.com/freebsd/pkg did not prove useful; does anyone understand what 
broke (and how to fix it)?

I ran into this because I use a cron job to archive poudriere build 
trees; the job does a diff -r of the latest pkg tree vs. the most recent 
archived tree (to decide if the new tree is worth archiving).

		Craig

iron 32 # pwd
/usr/local/poudriere/data/packages/12release-current-patched
iron 33 # find . -name '*.sig'
./.real_1627222758/Latest/pkg.txz.sig
iron 34 # ls -l .real_1627222758/Latest/pkg.txz.sig
lrwxr-xr-x 1 root wheel 11 Jul 25 06:01 
.real_1627222758/Latest/pkg.txz.sig -> pkg.pkg.sig
iron 35 # : < .real_1627222758/Latest/pkg.txz.sig
.real_1627222758/Latest/pkg.txz.sig: No such file or directory.