I had the same problem using CentOS 6 with supervisor 2. I will assume you run a similar configuration.
In my case, upgrading solved the problem. However, there are no available up to date supervisord binary package for my system. So here is how I have updated:
First, download the following source RPM supervisor-3.0-0.5.a10.fc16.src.rpm
(available here: http://dl.fedoraproject.org/pub/fedora/linux/releases/16/Everything/source/SRPMS/supervisor-3.0-0.5.a10.fc16.src.rpm). If you try a more recent source package, the build might fail and you might run into a dependencies hell.
Install rpm-build
package using:
yum install rpm-build
Then try to build using the following command,
rpmbuild --rebuild supervisor-3.0-0.5.a10.fc16.src.rpm
If this fails, install any needed dependency using yum.
yum install <dependencies>
Then try to build again:
rpmbuild --rebuild supervisor-3.0-0.5.a10.fc16.src.rpm
You will then be able to install supervisord and the problem will disappear !
yum install ~/rpmbuild/RPMS/noarch/supervisor-3.0-0.5.a10.el6.noarch.rpm