Fixes malformed url problem querying etcd

This fixes a problem in which a malformed path lookup in etcd could return negative results if a key is found in a subsequent path.

Way to reproduce

1. Edit hiera.yaml and add a path with a variable that doesn't exist or malformed

    :http:
      :host: 127.0.0.1
      :port: 4001
      :paths:
        - /configuration/defaults
        - /configuration/%{fqdn}
        - /configuration/%{environmentfake}
        - /configuration/common

2. Perform a hiera lookup into etcd, for a key, if they key is available under /configuration/common/keyname it won't be found as the previous paths had variables that didn't expand and ended up with "//"

Another way to solve the issue would be to deduplicate the "//" into "/" but that would have unpredictable results