contrib/examples/git-fetch.sh: use the $( ... ) construct for command substitution

The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.

The backquoted form is the traditional method for command
substitution, and is supported by POSIX.  However, all but the
simplest uses become complicated quickly.  In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.

The patch was generated by:

for _f in $(find . -name "*.sh")
do
	perl -i -pe 'BEGIN{undef $/;} s/`(.+?)`/\$(\1)/smg'  "${_f}"
done

and then carefully proof-read.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/examples/git-fetch.sh

@@ -146,13 +146,13 @@ esac
 reflist=$(get_remote_refs_for_fetch "$@")
 if test "$tags"
 then
-	taglist=`IFS='	' &&
+	taglist=$(IFS='	' &&
 		  echo "$ls_remote_result" |
 		  git show-ref --exclude-existing=refs/tags/ |
 	          while read sha1 name
 		  do
 			echo ".${name}:${name}"
-		  done` || exit
+		  done) || exit
 	if test "$#" -gt 1
 	then
 		# remote URL plus explicit refspecs; we need to merge them.