[filer.copy] argument -collection not taken into account when passed after directory to copy.

[bmillemathias]

Describe the bug
on a fresh cluster I've launched a command filer.copy with a collection parameter but the files were is the collection ""

weed -v 4 filer.copy  ../../Music/* -collection music http://xxx.xxx.xxx.xxx:8888/collections/music/
(copy in progress)
...

weed shell -master xxx.xxx.xxx.xxx:9333
> collection.list
collection:""
Total 1 collections.

System Setup

• config: 3 masters, 3 volumes servers (connected to all masters), 3 filer (connected to all masters and connected to other peer)
• List the command line to start "weed master", "weed volume", "weed filer", "weed s3", "weed mount".
  • masters: weed -v 2 master -mdir /opt/seaweedfs/weed.domain.tld/master -port 9333 --peers ip-1:9333,ip-2:9333,ip-3:9333 -defaultReplication 001
  • volumes: weed -v 2 volume -dir /opt/seaweedfs/weed.domain.tld/volume -dataCenter=DefaultDataCenter -rack=DefaultRack -mserver ip-1:9333,ip-2:9333,ip-3:9333
  • filers: weed -v 2 filer -dataCenter=DefaultDataCenter -rack=DefaultRack -master ip-1:9333,ip-2:9333,ip-3:9333 --peers ip-1:8888,ip-2:8888,ip-3:8888 -encryptVolumeData
• OS version: Linux ubuntu 18.04
• output of weed version: 2.15
• if using filer, show the content of filer.toml: empty

Expected behavior
Have the collection set for file transfered.

[bmillemathias]

Actually the order of argument matters so -collection ... has to be passed before the directory.
It's a bit misleading the command silently discard it, and the help does not even states where the options has to be passed in the command-line.

[chrislusf]

I added a fix to show error a little bit more obviously.