scripts: Detect remote branch to fetch submodules from
scripts: Detect remote branch to fetch submodules from

There's a script to automate fetching submodule changes. However, this
script alays fetches remote master branch, which's not always the case.
The correct branch can be detected by checking the current remote
tracking scylla branch which should coincide with the submodule one.

Signed-off-by: Pavel Emelyanov <c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>
Message-Id: <20220317085018.11529-1-c9a32589e048e044184536f7ac71ef92fe82df3e@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla