extreme long puppet run in case of selinux and lots of mounts

It seems that for almost every file that puppet encounters, it checks for selinux attributes, and by doing so it will scan the complete /proc/mounts in chunks of 1024 bytes to try to determine the filesystem type. 

So on any server that has selinux activated and more than 1000 mounts, puppet will use huge amounts of CPU and take ages…

I've created a a small patch that caches results. On some servers puppet run went from 2 hours to 10 minutes!

$ diff /opt/puppetlabs/puppet/lib/ruby/vendor_ruby/puppet/util/selinux.rb selinux_patched.rb
16c16,18
< def self.selinux_support?
—
> $mounts = {}
>
> def selinux_support?
24,27d25
< def selinux_support?
< Puppet::Util::SELinux.selinux_support?
< end
<
209,211c207
< loop do
< mounts += mountfh.read_nonblock(1024)
< end
—
> mounts += mountfh.read_nonblock(1024) while true
241c237,244
< return nil unless mounts = read_mounts
—
>
> if $mounts.empty?
> # fill $mounts hash if still empty.
> # Most probably only executed the first time this function is called.
> $mounts = {} unless $mounts = read_mounts
> end
>
> return nil if mounts.empty?
254c257
< return mounts[segment.to_s] if mounts.has_key?(segment.to_s)
—
> return $mounts[segment.to_s] if $mounts.has_key?(segment.to_s)