[feature request] provide commit range for the whole pull request

[sibelius]

Orb version

1.0.2

What happened

It is not showing whole commit range for pull requests

Expected behavior

This is the commits for my pull requests

CIRCLE_COMPARE_URL=$(cat CIRCLE_COMPARE_URL.txt)
 COMMIT_RANGE=$(echo $CIRCLE_COMPARE_URL | sed 's:^.*/compare/::g')
 echo "Commit range: $COMMIT_RANGE"

compare url is like this: 068728a95a46...3466429, in the latest commit.
but it should be 29a7e130f034...068728a95a46

We need this because we cancel jobs on pull requests if another commit show up, so we need to run tests based on the whole pull request commit range