dist/ubuntu: Fix the init script variable sourcing
dist/ubuntu: Fix the init script variable sourcing

The variable sourcing was crashing the init script on ubuntu.
Fix it with the suggestion from Avi.

Signed-off-by: Benoît Canet <ecd1f14f7c1c6dc7a40210bdcc3810e0107ecbc8@scylladb.com>
Message-Id: <1458685099-1160-1-git-send-email-ecd1f14f7c1c6dc7a40210bdcc3810e0107ecbc8@scylladb.com>

scylladb/scylla,raphaelsc/scylla,duarten/scylla,scylladb/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,kjniemi/scylla,raphaelsc/scylla,raphaelsc/scylla,scylladb/scylla,kjniemi/scylla,kjniemi/scylla,duarten/scylla,avikivity/scylla,avikivity/scylla