Pluginsync errors when no source is available and modulepath directory is a symlink

Context

Currently, Puppet produces one of two pluginsync errors during an agent run if the root of a modulepath directory is a symlink and no modules contain a facts.d or lib directory.

In the normal case, when the base module path is a directory and none if its modules include facts.d or lib directories, pluginsync returns the path to the module path directory itself, at which point the file type disables recursion in its `recurse_remote` method and stops the agent from attempting to download plugins.

However, if the base module path is not a directory (in this case a link), `recurse_remote` returns early, causing the agent-side facts.d or lib directory to not have its 'source' metadata set, leading to a failing query back to the master.

Steps to reproduce

1) Install any version of Puppet from 3.5.1 onward
2) Edit puppet.conf to look like the following (where this is both the master and the agent):

[main]

    logdir = /var/log/puppet

    rundir = /var/run/puppet

    ssldir = $vardir/ssl

    server = miyxwpjl6z3zkmn.delivery.puppetlabs.net

    basemodulepath = /usr/share/puppet/modules:/h/puppet_modules

    environmentpath = $confdir/environments

[agent]

    classfile = $vardir/classes.txt

    localconfig = $vardir/localconfig

    pluginsync = true

    environment = production

3) mkdir -p /h/puppet_modules
4) mkdir -p /etc/puppet/environments/production
5) ln -s /h/puppet_modules /etc/puppet/environments/production/modules
6) puppet module install puppetlabs-stdlib
7) Start the master with puppet master --verbose --no-daemonize
8) Run the agent with puppet agent -t

To "fix" the error, simply run mkdir /h/puppet_modules/stdlib/facts.d.

Output

[root@foupsthuyg3ci5r ~]# puppet agent -t

Info: Retrieving pluginfacts

Error: /File[/var/lib/puppet/facts.d]: Could not evaluate: Could not retrieve information from environment production source(s) puppet://foupsthuyg3ci5r.delivery.puppetlabs.net/pluginfacts

Info: Retrieving plugin

Error: /File[/var/lib/puppet/lib]: Could not evaluate: Could not retrieve information from environment production source(s) puppet://foupsthuyg3ci5r.delivery.puppetlabs.net/plugins

Info: Caching catalog for foupsthuyg3ci5r.delivery.puppetlabs.net

Info: Applying configuration version '1422752263'

Notice: Finished catalog run in 0.04 seconds