dbscripts: allow sourceballs to create a lockfile

/srv/repos/lock is the lock file location configured via a dbscripts config. Only accessible for users in junior-packager group, a lot better would be if sourceballs could write a lock file into /run/sourceballs.lck as it is unrelated to /srv/repos.

mentioned in issue #572 (closed)

added 363 commits

• e589a87a...6efdac07 - 362 commits from branch master
• 199cc1fc - dbscripts: allow sourceballs to create a lockfile

Compare with previous version

mentioned in commit a56d17e4

merged