pr_checker: ignore private emails

[joyeecheung]

Refs: nodejs/node#15489

[joyeecheung]

Oh, this needs a test, coming

[codecov]

Codecov Report

Merging #121 into master will increase coverage by 0.21%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #121      +/-   ##
==========================================
+ Coverage   91.11%   91.32%   +0.21%     
==========================================
  Files          14       14              
  Lines         540      542       +2     
==========================================
+ Hits          492      495       +3     
+ Misses         48       47       -1

Impacted Files	Coverage Δ
lib/pr_checker.js	97.59% <100%> (+0.63%)	⬆️

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[joyeecheung]

Also print the email and the status of the author requested by @targos

[joyeecheung]

Appveyor and Travis are happy, merging

[targos]

thanks!