bash-completion: (umount) use findmnt, escape a space in paths

# mount /dev/sdc1 /mnt/test/foo\ bar
 # umount <tab>

has to return "/mnt/test/foo\ bar".

Changes:

 * don't use mount | awk output, we have findmnt
 * force compgen use \n as entries separator

Addresses: https://github.com/karelzak/util-linux/issues/539
Signed-off-by: Karel Zak <kzak@redhat.com>

bash-completion/umount

@@ -40,9 +40,10 @@ _umount_module()
 			return 0
 			;;
 	esac
-	local DEVS_MPOINTS
-	DEVS_MPOINTS="$(mount | awk '{print $1, $3}')"
-	COMPREPLY=( $(compgen -W "$DEVS_MPOINTS" -- $cur) )
-	return 0
+
+	local oldifs=$IFS
+	IFS=$'\n'
+	COMPREPLY=( $( compgen -W '$(findmnt -lno TARGET | sed "s/\([[:blank:]]\)/\\\\\1/g")' -- "$cur" ) )
+	IFS=$oldifs
 }
 complete -F _umount_module umount