That error is from 'cd bindings/ruby && ruby extconf.rb --vendor' BTW.
Subject: Re: [patch v3 1/4] build: integrate building ruby bindings into notmuch build process
Date: Sat, 13 Jun 2015 14:24:09 -0700
To: David Bremner, notmuch@notmuchmail.org
Cc:
From: Jinwoo Lee
That error is from 'cd bindings/ruby && ruby extconf.rb --vendor' BTW.