mysqldump adds the "-- Dump completed on YYYY-MM-DD hh:mm:ss" string
to the end of output if the --comments switch is on.
The only way to suppress this line is to use --skip-comments/--compact
switch.

New switch has been added to the mysqldump client command line:
--dump-date.

For the compatibility with previous releases, by default the --dump-date
is on.
The --dump-date switch forces mysqldump to add date to the
"-- Dump completed on ..." string at the end of output.
The --skip-dump-date switch supresses the output of date string
and uses short form of that commentary: "-- Dump completed".
--skip-comments or --compact switches disable the whole commentary
as usual.