This was caused by a change to the upstream library
ProtonMail/go-crypto checking the flags on the keys more strictly.
However the signing key for rclone is very old and does not have those
flags. Adding those flags using `gpg --edit-key` and then the
`change-usage` subcommand to remove, save, quite then re-add, save
quit the signing capabilities caused the key to work.
This also adds tests for the verification and adds the selfupdate
tests into the integration test harness as they had been disabled on
CI because they rely on external sources and are sometimes unreliable.
Fixes#7373
This replaces built-in os.MkdirAll with a patched version that stops the recursion
when reaching the volume part of the path. The original version would continue recursion,
and for extended length paths end up with \\? as the top-level directory, and the error
message would then be something like:
mkdir \\?: The filename, directory name, or volume label syntax is incorrect.
