Fix upstream branch setting in "%autosetup -S git"

If the repo is already initialized when calling this macro and it's
using a different branch name than "master" (see #2121) or the global
git option init.defaultBranch is set differently (see #2120), the macro
will fail at:

    %{__git} branch --set-upstream-to=master

Instead of being overly clever, just track the original (start-point)
branch by using --track when branching (see git-branch(1) for details).

For brevity, combine this and branch creation into a single checkout
command.

This fixes commit 3a6b1d8fbf846d3f1b139d343fdfddebe99ae42b.

Thanks Panu for the clarification and suggestion in #854!

(cherry picked from commit 1f5ae2a6dd710de4a278087471bf0909ff9f6739)

1 files changed, 1 insertions, 3 deletions

diff --git a/macros.in b/macros.in
index d53ab5ed5..827e9a473 100644
--- a/macros.in
+++ b/macros.in
@@ -1164,9 +1164,7 @@ package or when debugging this package.\
 %{__git} add --force .\
 %{__git} commit %{-q} --allow-empty -a\\\
 	--author "%{__scm_author}" -m "%{NAME}-%{VERSION} base"\
-%{__git} branch rpm-build \
-%{__git} checkout rpm-build \
-%{__git} branch --set-upstream-to=master
+%{__git} checkout --track -b rpm-build
 
 %__scm_apply_git(qp:m:)\
 %{__git} apply --index --reject %{-p:-p%{-p*}} -\