CVE-2026-71464 [LOW] – LaunchConfigurationBaseSerializer.scm_branch has no validate_scm_branch() le

LaunchConfigurationBaseSerializer.scm_branch has no
validate_scm_branch() leading-dash check, unlike
Project/JobTemplate/JobLaunch serializers. Schedule and
WFJT Node accept –upload-pack=/bin/id as scm_branch.
Currently blocked at runtime by jobs.py:1502 ValueError
check (defense-in-depth), but the API validation gap
means sole reliance on a task-layer guard. Refactoring
that guard away would promote this to RCE.