get_author_ident_from_commit(): remove useless quoting

get_author_ident_from_commit(): remove useless quoting

The command 's/'\''/'\''\'\'\''/g' only triples single quotes:

	$ echo "What's up?" | sed 's/'\''/'\''\'\'\''/g'
	What'''s up?

This doesn't hurt as compared to a single single quote it only adds an
empty string, but it makes the script needlessly complicated and hard to
understand.  The useful quoting is done by s/'\''/'\''\\'\'\''/g at the
beginning of the script and only once for all three variables.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>