Make default pre-commit hook less noisy

This hook thought to have found a conflict marker any time it saw
a 7-character combination of any of the characters '<>=' at the
beginning of a line, whereas it should only look for the *same*
character to appear repeatedly.

Also, restrict it to match exactly 7 times, to avoid matching the
underlining with '='-characters often used in documentation.

Signed-off-by: Jean-Luc Herren <jlh@gmx.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

templates/hooks--pre-commit

@@ -61,7 +61,7 @@ perl -e '
 	    if (/^\s* \t/) {
 		bad_line("indent SP followed by a TAB", $_);
 	    }
-	    if (/^(?:[<>=]){7}/) {
+	    if (/^([<>])\1{6} |^={7}$/) {
 		bad_line("unresolved merge conflict", $_);
 	    }
 	}