utils: If shell.run_parallel is not called before run.shell(), then the

lock is not initialized. Thus, we initialize the lock to None and just
don't use it because no console output can happen in parallel because
we're not running in parallel.

Author: Doug Coleman

utils/swift_build_support/swift_build_support/shell.py

@@ -175,6 +175,9 @@ def copytree(src, dest, dry_run=None, echo=True):
     shutil.copytree(src, dest)
 
 
+# Initialized later
+lock = None
+
 def run(*args, **kwargs):
     repo_path = os.getcwd()
     echo_output = kwargs.pop('echo', False)
@@ -189,7 +192,8 @@ def run(*args, **kwargs):
     (stdout, stderr) = my_pipe.communicate()
     ret = my_pipe.wait()
 
-    lock.acquire()
+    if lock:
+        lock.acquire()
     if echo_output:
         print(repo_path)
         _echo_command(dry_run, *args, env=env)
@@ -198,7 +202,8 @@ def run(*args, **kwargs):
         if stderr:
             print(stderr, end="")
         print()
-    lock.release()
+    if lock:
+        lock.release()
 
     if ret != 0:
         eout = Exception()