[buildbot] phase1: improve Git cloning on the master

[LEDE Commits]

jow pushed a commit to buildbot.git, branch master:
https://git.lede-project.org/a24d662ed51d52d13005fc390932d50942aa0655

commit a24d662ed51d52d13005fc390932d50942aa0655
Author: Jo-Philipp Wich <jo at mein.io>
AuthorDate: Mon Nov 28 19:28:07 2016 +0100

    phase1: improve Git cloning on the master
    
    Avoid switching branches later and checkout the proper branch right away.
    
    Signed-off-by: Jo-Philipp Wich <jo at mein.io>
---
 phase1/master.cfg | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/phase1/master.cfg b/phase1/master.cfg
index 2e7c195..2ae92f1 100644
--- a/phase1/master.cfg
+++ b/phase1/master.cfg
@@ -96,10 +96,8 @@ if ini.has_option("gpg", "passfile"):
 targets = [ ]
 
 if not os.path.isdir(home_dir+'/source.git'):
-	subprocess.call(["git", "clone", "--depth=1", repo_url, home_dir+'/source.git'])
-	subprocess.call(["git", "checkout", repo_branch], cwd = home_dir+'/source.git')
+	subprocess.call(["git", "clone", "--depth=1", "--branch="+repo_branch, repo_url, home_dir+'/source.git'])
 else:
-	subprocess.call(["git", "checkout", repo_branch], cwd = home_dir+'/source.git')
 	subprocess.call(["git", "pull"], cwd = home_dir+'/source.git')
 
 findtargets = subprocess.Popen([home_dir+'/dumpinfo.pl', 'targets'],