[hg] fault tolerant commit sha resolution

[WnP]

if terminfo is wrongly configured hg id -i --debug can return the following errors:

no terminfo entry for invis
no terminfo entry for blink
no terminfo entry for invis
no terminfo entry for blink
no terminfo entry for invis

Which causes vendir to fail to retrieve the commit sha.

Using hg log -r . -T '{node}' returns the same result and solves this issue.

[cppforlife]

will try to cut a release shortly (seeing if we can merge another open PR before that)

[cppforlife]

@WnP in https://github.com/vmware-tanzu/carvel-vendir/releases/tag/v0.28.0

[WnP]

Thanks a lot @cppforlife

[cppforlife]

ill share release glory with @DennisDenuto :)