This recommended update provides version 1.5.1 for rubygem-r10k:

- Version bump 1.5.1:
* 1.4.2:
* (RK-4) Raise meaningful errors on missing sources
* (GH-310, RK-36) r10k deploy display -p --detail fails on Ruby 1.8.7
https://github.com/puppetlabs/r10k/blob/master/CHANGELOG.mkd#142
* 1.5.0:
* (GH-57) Git based modules fail to detect presence of git binary
* (GH-195) (RK-35) Allow sources to specify a custom prefix string
* (RK-17) Add rugged/libgit2 based Git implementation
* (RK-24) Add '/etc/puppetlabs/r10k/r10k.yaml' to config search path
* (RK-25) Warn if both '/etc/r10k.yaml' and '/etc/puppetlabs/r10k/r10k.yaml' exist
* (RK-31) Remove undocumented search for 'r10k.yaml'
* (RK-32, RK-33, RK-38) Provide configuration options for Git providers
* (RK-37) Support higher verbosity levels for r10k version
* (RK-39, RK-66) Improved logging/messaging
* (RK-74) Improved log formatting
* (RK-75) Optional log coloring
* (GH-265) (RK-11) Unix commands with > 64KiB of output no longer deadlock
* (GH-142) Use Forge v3 API
* (RK-16) Decouple Git platform dependent and independent code
* (RK-55, GH-355) Prevent warnings on Ruby 2.2
* (RK-65) Switch to using the semantic_puppet gem
* (RK-48) Ignore deleted versions when fetching latest module version
https://github.com/puppetlabs/r10k/blob/master/CHANGELOG.mkd#150
* 1.5.1:
* (RK-62) Warn when Rugged is compiled without SSH or HTTPS transports
* (RK-79) Bump minimum required version of faraday_middlware-multi_json
* (RK-86) Git modules don't properly track branches
https://github.com/puppetlabs/r10k/blob/master/CHANGELOG.mkd#151
- Recommend the puppetmaster instead of require, because:
- r10k can be used only for syntax checking of the Puppetfile
- puppetserver is an alternative to puppetmaster