The two scripts disagreed on an old packaged Desktop's v1 bridge (round 5
D11): bash adopted a live launcher that is our parent but no longer the
Desktop's child when line 2 equals HERMES_UPDATE_STARTED_AT (the Desktop
quit first and the launcher was re-parented); PowerShell refused it, also
accepted a v2/delegate claim naming its parent, required a gone launcher to
be its recorded parent, and Trim()/TryParse'd the env value.
One rule now, as a pure function in both (marker_launcher_rule /
Test-MarkerLauncherRule) over the same facts, plus one env comparison
(plain ASCII digits of line 2's value). tests/scripts/desktop_update/
lineage_rule_cases.py is the shared table; the posix and Windows suites run
it, and a real-process cell per platform covers the divergent row.
(cherry picked from commit aa4b8ce704bc474d539690235c191edee3b637f2)
33cea9a733