run-tests: move newline out of colorized message The leading newline before "ERROR:" led to an incorrect lexing of the message and the newline got lost. The fixed formatting can be seen in the test case. The reason we didn't notice before was that the bad formatting just led to the loss of a blank line in the test. However, there are other cases where it would be joined with a line saying "Accept this change? [n]" or "Reference output has changed (run again to prompt changes)". Differential Revision: https://phab.mercurial-scm.org/D1159