Substitute placeholders `esrA` and `esrB` with actual commit hashes.
`esrA` is replaced with the commit tagged as
tor-browser-68.12.0esr-10.0-1-build1, and `esrB` is replaced as the last
audited commit for 78.6.1esr (tagged on FIREFOX_ESR_78_6_X_RELBRANCH).