Setting system mercurial in Sourcetree preferences results in 'Mercurial Not Found'

Issue Summary

This is reproducible on Data Center: (yes) / (no)

The issue has been explained here: https://atlassian.slack.com/archives/CFH6PR6CV/p1665996461721189?thread_ts=1665995792.299089&cid=CFH6PR6CV 

Possibly related: https://jira.atlassian.com/browse/SRCTREE-7593

Steps to Reproduce

1. Selected Preferences > Mercurial > Use System Mercurial.
2. Navigated to the system mercurial package.

Expected Results

1. Mercurial should have been used.

Actual Results

'Mercurial Not Found'

Workaround

Do not have a workaround for this yet.