Fix up subprocess calls

subprocess.call() does not by default return a status value.

Update the commands to add shell=True which forces a return value.
Also convert the commands to a single string rather than a list as
this plays more nicely with both linux and windows.

Also fix a spurious :

Author: adbridge

tools/test/examples/examples_lib.py

@@ -168,8 +168,10 @@ def source_repos(config, examples):
                 if os.path.exists(name):
                     print("'%s' example directory already exists. Deleting..." % name)
                     rmtree(name)
+                
+                cmd = "mbed-cli import %s" %repo_info['repo']
+                result = subprocess.call(cmd, shell=True)
 
-                result = subprocess.call(["mbed-cli", "import", repo_info['repo']])
                 if result:
                     return result
 
@@ -191,8 +193,9 @@ def clone_repos(config, examples , retry = 3):
                 if os.path.exists(name):
                     print("'%s' example directory already exists. Deleting..." % name)
                     rmtree(name)
+                cmd = "%s clone %s" %(repo_info['type'], repo_info['repo'])
                 for i in range(0, retry):
-                    if subprocess.call([repo_info['type'], "clone", repo_info['repo']]) == 0:
+                    if not subprocess.call(cmd, shell=True):                        
                         break
                 else:
                     print("ERROR : unable to clone the repo {}".format(name))
@@ -213,7 +216,7 @@ def deploy_repos(config, examples):
             if name in examples:
                 if os.path.exists(name):
                     os.chdir(name)
-                    result = subprocess.call(["mbed-cli", "deploy"])
+                    result = subprocess.call("mbed-cli deploy", shell=True)
                     os.chdir("..")
                     if result:
                         print("mbed-cli deploy command failed for '%s'" % name)
@@ -415,10 +418,11 @@ def update_mbedos_version(config, tag, examples):
             update_dir =  basename(repo_info['repo']) + "/mbed-os"
             print("\nChanging dir to %s\n" % update_dir)
             os.chdir(update_dir)
-            result = subprocess.call(["mbed-cli", "update", tag, "--clean"])
+            cmd = "mbed-cli update %s --clean" %tag
+            result = subprocess.call(cmd, shell=True)
             os.chdir("../..")
             if result:
-                return result:
+                return result
 
     return 0