linkahead.service starts a login shell that starts a python script

Summary

/lib/systemd/system/linkahead.service for some reason starts a login shell which then starts a python script.

ExecStart=/bin/sh -l -c "/usr/bin/linkahead start --no-health --no-build"
ExecStop=/bin/sh -l -c "/usr/bin/linkahead stop"

Is there a reason for this? This breaks our deployment (our fault) so I wrote an overwrite for the unit:

# /etc/systemd/system/linkahead.service.d/override.conf
[Service]
ExecStart=
ExecStart=usr/bin/linkahead start --no-health --no-build
ExecStop=/usr/bin/linkahead stop

This seems to works fine, but I was wondering why a login shell is started by the service in the first place. 🤷