Glance skip prompting if stdin isn't a tty

Don't have glance issue prompts if stdin isn't a tty.  Fixes bug 884116.

In glance's user_confirm routine, check if stdin is a tty and if
not, just return the default value. If it is a tty, then continue
with the raw_input call to issue the prompt and get the response.
Latest patch includes recommended change to check for isatty attr before
using it.

Added myself to Authors.

Change-Id: I8134668b8382b44618c86972190f3d7d98f55e52

Authors

@@ -27,6 +27,7 @@ Josh Kearney <josh@jk0.org>
 Justin Santa Barbara <justin@fathomdb.com>
 Justin Shepherd <jshepher@rackspace.com>
 Ken Pepple <ken.pepple@gmail.com>
+Ken Thomas <krt@yahoo-inc.com>
 Kevin L. Mitchell <kevin.mitchell@rackspace.com>
 Lorin Hochstein <lorin@isi.edu>
 Major Hayden <major@mhtx.net>

bin/glance

@@ -999,6 +999,10 @@ def user_confirm(prompt, default=False):
     else:
         prompt_default = "[y/N]"
 
+    # for bug 884116, don't issue the prompt if stdin isn't a tty
+    if not hasattr(sys.stdin, 'isatty') or not sys.stdin.isatty():
+        return default
+
     answer = raw_input("%s %s " % (prompt, prompt_default))
 
     if answer == "":