osmo-deps.sh: fix: add 'origin/' to branch, to properly update

If I have a git clone that once did 'checkout [-f] branch', and if then
origin/branch gets updates, doing another 'checkout -f branch' only goes back
to the local tracking-branch of origin/branch. We never pull in changes from
origin/branch anymore as soon as a local branch exists. Always prepend
'origin/', so that 'checkout -f' goes into detached-HEAD state onto the newest
fetched revision.

Change-Id: Ia715a100b5beaf7e612c2c64cdad8819aa00c8bd

scripts/osmo-deps.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 set -ex
 project="$1"
-branch="${2:-origin/master}"
+branch="origin/${2:-master}"
 
 if ! test -d "$project";
 then