common_code: GIT_BRANCH_NAME = GIT_BRANCH only if not already given

diff --git a/common_code.py b/common_code.py
index 403c35d6739b608814cc70f24252a7a725bdee48..f2ad5d8ee8fe8895f6c484ccc34034ccf1d14a51 100755 (executable)
--- a/common_code.py
+++ b/common_code.py
@@ -48,7 +48,7 @@ def exit_error():
 ENV = os.environ
 ENV.setdefault('ARGV',' '.join(sys.argv))
 ENV.setdefault('CWD',os.getcwd())
-ENV['GIT_BRANCH_NAME'] = ENV['GIT_BRANCH']
+ENV.setdefault('GIT_BRANCH_NAME', ENV['GIT_BRANCH'])
 
 BIN_DCH = '/usr/bin/dch'
 BIN_DPUT = '/usr/bin/dput'