Output error if command fails

scripts/gendoc.py

@@ -32,7 +32,9 @@ def rst2html(i, o):
             )
 
 def run_through_template(input):
-    null = open(os.devnull, 'w')
+    tmpfile = './tmp/output'
+    try:
+        with open(tmpfile, 'w') as out:
             subprocess.check_output(
                 [
                     'python', 'build.py',
@@ -40,9 +42,13 @@ def run_through_template(input):
                     "-o", "../scripts/tmp",
                     "../scripts/"+input
                 ],
-        stderr=null,
+                stderr=out,
                 cwd="../templating",
             )
+    except subprocess.CalledProcessError as e:
+        with open(tmpfile, 'r') as f:
+            print f.read()
+        raise
 
 def prepare_env():
     try: