prerm is in git-daemon-sysvinit 1:1.9.1-1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 | #!/bin/sh
set -e
test "$1" = 'remove' || test "$1" = 'deconfigure' || \
  test "$1" = 'failed-upgrade' || exit 0
if [ -x "/etc/init.d/git-daemon" ]; then
	if [ -x "`which invoke-rc.d 2>/dev/null`" ]; then
		invoke-rc.d git-daemon stop || exit $?
	else
		/etc/init.d/git-daemon stop || exit $?
	fi
fi
 |