[PATCH] scripts: Fix git-checkout.sh to work with branches other than master

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Xen uses master for QEMU_UPSTREAM_REVISION, and has done for other trees too
in the path.  Apparently we've never specified a different branch, because the
git-clone rune only pulls in the master branch; it does not pull in diverging
branches.  Fix this by stating which branch/tag is wanted.

$TAG is really a committish, and git-clone's -b/--branch takes a committish
too.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
CC: Juergen Gross <jgross@xxxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>

Found while trying to test the MiniOS fixes in Gitlab.  This is a example run
with most stubdom builds passing:

  https://gitlab.com/xen-project/people/andyhhp/xen/-/pipelines/1520611847

and all of them successfully cloned.
---
 scripts/git-checkout.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/git-checkout.sh b/scripts/git-checkout.sh
index fd4425ac4ee8..3796cbfe39a7 100755
--- a/scripts/git-checkout.sh
+++ b/scripts/git-checkout.sh
@@ -14,7 +14,7 @@ set -e
 if test \! -d $DIR-remote; then
        rm -rf $DIR-remote $DIR-remote.tmp
        mkdir -p $DIR-remote.tmp; rmdir $DIR-remote.tmp
-       $GIT clone $TREE $DIR-remote.tmp
+       $GIT clone -b $TAG $TREE $DIR-remote.tmp
        if test "$TAG" ; then
                cd $DIR-remote.tmp
                $GIT branch -D dummy >/dev/null 2>&1 ||:

base-commit: bb7296d77f171c7bfbafab30ed51e9be29660e39
-- 
2.39.5