Change parse error to output a single line log [changelog skip]

[lucaspiller]

Description

This changes the error when an HTTP parse error is encountered so it outputs a single line to the error log. Our logging system (Loggly) expects a single line per error, and it doesn't support filtering the second line (---) as it contains special characters. As discussed in #986 we experience these errors often on AWS, so is causing a lot of noise for us.

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[nateberkopec]

Yeah, that extra line is a little wacky. This will probably get fixed anyway by #2250, but I'll merge this until then.