Try and get a valid branch name on jenkins

getversion.py

@@ -47,13 +47,16 @@ def main():
 
     (mcpversion,mcclientversion,mcserverversion) = re.match("[.\w]+ \(data: ([.\w]+), client: ([.\w.]+), server: ([.\w.]+)\)",Commands.fullversion()).groups()
     
-    cmd = "git rev-parse --abbrev-ref HEAD"
-    try:
-      process = subprocess.Popen(cmdsplit(cmd), stdout=subprocess.PIPE, stderr=subprocess.STDOUT, bufsize=-1)
-      branch, _ = process.communicate()
-    except OSError:
-      print("Git not found")
-      branch="none"
+    if os.getenv("GIT_BRANCH") is None:
+      cmd = "git rev-parse --abbrev-ref HEAD"
+      try:
+        process = subprocess.Popen(cmdsplit(cmd), stdout=subprocess.PIPE, stderr=subprocess.STDOUT, bufsize=-1)
+        branch, _ = process.communicate()
+      except OSError:
+        print("Git not found")
+        branch="none"
+    else:
+      branch=os.getenv("GIT_BRANCH")
 
     with open("fmlversion.properties","w") as f:
       f.write("%s=%s\n" %("fmlbuild.major.number",major))