Running Mercurial with a custom Python version: version mismatch

[Thomas De Schampheleire]

Hi,

Commits 3681de20b0a7 / 21dafd8546d1 ("parsers: fail fast if Python has
wrong minor version (issue4110)") introduced a check on the running
Python version. If the version doesn't match the version Mercurial was
compiled with, the operation is aborted.

This implies that a user can no longer use Mercurial with a custom
Python version, or use a custom Mercurial version without updating
Python. Suppose Mercurial is installed by the distro, but the user
installs a custom Python in his PATH. Or the user wishes to test a
newer version of Mercurial but remains with the distro-provided Python
version.

How is this supposed to be handled?

Surely it should be acceptable for a user to have a custom Python
configured in his shell, but let Mercurial use the 'old' Python
provided by the distro if it was installed with that, right?

Thanks,
Thomas