git-fetch --upload-pack: disambiguate.

Johannes noticed the recent addition of this new flag
inadvertently took over existing --update-head-ok (-u).  Require
longer abbreviation to this new option which would be needed in
a rare setup.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/fetch-options.txt

@@ -3,8 +3,7 @@
 	existing contents of `.git/FETCH_HEAD`.  Without this
 	option old data in `.git/FETCH_HEAD` will be overwritten.
 
---upload-pack <upload-pack>::
--u <upload-pack>::
+\--upload-pack <upload-pack>::
         When given, and the repository to fetch from is handled
         by 'git-fetch-pack', '--exec=<upload-pack>' is passed to
         the command to specify non-default path for the command

git-fetch.sh

@@ -25,8 +25,8 @@ do
 	-a|--a|--ap|--app|--appe|--appen|--append)
 		append=t
 		;;
-	-u|--u|--up|--upl|--uploa|--upload|--upload-|--upload-p|--upload-pa|\
-	--upload-pac|--upload-pack)
+	--upl|--uplo|--uploa|--upload|--upload-|--upload-p|\
+	--upload-pa|--upload-pac|--upload-pack)
 		shift
 		exec="--exec=$1" 
 		upload_pack="-u $1"