Fix two minor issues

Summary:
Ref T7811. Fixes two minor issues I observed in the cluster:

• Sometimes APC doesn't give us key names. Not sure exactly what's up here, but we can do a better job with this.
• The % in 25% actually needs more escaping, since it's interpreted by both pht() (immediately) and console_format() (later).

Test Plan:

• First one is just from an error log, not sure how to repro offhand.
• Ran bin/phd help start for the second one.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7814, T7811

Differential Revision: https://secure.phabricator.com/D12395