Wrap exceptions that occur while running external process

This should help identify problem with timeouts.

Change-Id: I663b1ca3fe9a74ed0869fefdb16583951e3db6a5

git_review/tests/utils.py

@@ -15,6 +15,7 @@
 
 import os
 import subprocess
+import traceback
 
 
 def run_cmd(*args, **kwargs):
@@ -25,6 +26,7 @@ def run_cmd(*args, **kwargs):
         def preexec_fn():
             return os.chdir(kwargs['chdir'])
 
+    try:
         proc = subprocess.Popen(args, stdin=subprocess.PIPE,
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT, env=os.environ,
@@ -36,6 +38,11 @@ def run_cmd(*args, **kwargs):
 
         out, err = proc.communicate()
         out = out.decode('utf-8')
+    except Exception:
+        raise Exception(
+            "Exception while processing the command:\n%s.\n%s" %
+            (' '.join(args), traceback.format_exc())
+        )
 
     if proc.returncode != 0:
         raise Exception(