uptime_sec came from the clone directory's own mtime, but a running VM's
hypervisor can rewrite lock files under that same directory at any point,
resetting the mtime and pinning "up" near 0s for the VM's entire life --
worst exactly while a build is actively running, since that's when the VM
is busiest. The clone name already carries its own creation timestamp
(_make_clone_name, parsed back via parse_clone_name), set once and never
disturbed after -- prefer it, falling back to the old mtime read only for
a name that doesn't parse.
Simone
3da992119b