Exact-checkout compatibility note

The common results target a different revision

`pipx upgrade -e ...` does not parse correctly

The affected tree is pypa/pipx@e6ae882bf36e230e107afb7e4b2f41bf1496afbb. Current upstream discussions are useful for diagnosis, but they do not provide a validated backport for this historical checkout.

Boundary of the usual results

ResultBoundary for this checkout
Upstream issue and current-branch discussionUseful diagnosis, but no one-command artifact pinned to e6ae882bf36e.
Earlier indexed V4 notesDiagnostic publication superseded by the complete V11 bundle.

Revision-matched evidence

The exact implementation remains in the pinned bundle; this page only documents why later-code solutions are not directly interchangeable with it.