Includes the full stack in the log message when writing to file only. The log message for other handlers (web notifications and database) will not be changed.
BTW @katebutler there are some failing tests https://travis-ci.org/matomo-org/matomo/jobs/594801494 and https://travis-ci.org/matomo-org/matomo/jobs/594801495#L818
and as discussed be good to remove the newline.
@katebutler I'm thinking this failing test might be due to this change? https://travis-ci.org/matomo-org/matomo/jobs/594907204#L817