Don't duplicate stdout and stderr in verbose progress output

[rmunn]

HgRepository.GetTextFromQuery calls ExecuteErrorsOk, then prints the contents of stdout and stderr via progress.WriteVerbose if they aren't empty. However, ExecuteErrorsOk also prints stdout and stderr with progress.WriteVerbose if they aren't empty. This duplication does nothing but make it harder to find things in the Chorus output, and I suggest getting rid of the progress.WriteVerbose calls from HgRepository.GetTextFromQuery.