I've got evidence that multiple build hosts may be encountering this,
but here's one sample of a failure on build256-m2 (from
/var/log/puppet/run_puppet.log):

Error: Could not retrieve catalog from remote server: Error 400 on SERVER: Could not find template 'chrome_infra/templates/puppet/usr_local_bin_run_puppet.sh.erb' at /etc/puppet/modules/chrome_infra/manifests/puppet/debian.pp:59 on node build256-m2.golo.chromium.org
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

Regarding P1:  It's possible that this is causing a P0 failure that's
blocking a Chrome OS release, in which case, this needs P0 attention.

For reference, the two current P0 bugs are  bug 801211  and
 bug 801062 .

Thanks... fix is uploading now.

This isn't blocking anything, puppet is down.  Puppet runs hourly.  This is fine.

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/infra/puppet/+/a62a789c99d510712317bb4bf353bff5234323a4

commit a62a789c99d510712317bb4bf353bff5234323a4
Author: Elliott Friedman <friedman@google.com>
Date: Thu Jan 11 21:55:42 2018

before:
chrome-bot@build256-m2:(Linux 14.04):~ PUPPET_FAILURES$ sudo puppet agent -t
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Loading facts
Fact file /var/lib/puppet/facts.d/windows_defender.ps1 was parsed but returned an empty data set
Error: Could not retrieve catalog from remote server: Error 400 on SERVER: Could not find template 'chrome_infra/templates/puppet/usr_local_bin_run_puppet.sh.erb' at /etc/puppet/modules/chrome_infra/manifests/puppet/debian.pp:59 on node build256-m2.golo.chromium.org
Warning: Not using cache on failed catalog
Error: Could not retrieve catalog; skipping run

after:
chrome-bot@build256-m2:(Linux 14.04):~ PUPPET_FAILURES$ sudo puppet agent -t
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Loading facts
Fact file /var/lib/puppet/facts.d/windows_defender.ps1 was parsed but returned an empty data set
Info: Caching catalog for build256-m2.golo.chromium.org
Info: Applying configuration version '1515707837'
Notice: /Stage[main]/Chrome_infra::Packages::Cleanup_apt/Exec[Fix_missing_apt_keys]/returns: executed successfully
Notice: /Stage[main]/Chrome_infra::Packages::Cleanup_apt/Exec[apt_get_f_install]/returns: executed successfully
Notice: /Stage[main]/Chrome_infra::Packages::Cleanup_apt/Exec[apt_get_autoremove_apt_get_autoclean]/returns: executed successfully
Notice: /Stage[main]/Chrome_infra::Packages::Cleanup_apt/Exec[Fix_expired_apt_keys]/returns: executed successfully
Notice: Finished catalog run in 15.42 seconds