The `filename` magic param isn't always removed from the request

[Pawel Kosiec]

Description

The filename magic parameter sometimes isn't removed from the underlying request, which make some requests fail, e.g. when using signed URLs to GCS bucket.

Details

Based on the code, I believe all the "magic" parameters should be removed before making a request.
This is not the case in case of an URL to tar.gz directory, like this:

https://storage.googleapis.com/bucket/v1.0.0/binary_darwin_amd64.tar.gz

and configuration:

	getterCli := &getter.Client{
		Ctx:  ctx,
		Src:  url, // url with `filename` magic param
		Dst:  tmpDestPath,
		Pwd:  pwd,
		Mode: getter.ClientModeAny,
	}

I tracked the code execution, and it falls in the if which changes the mode:

go-getter/client.go

Line 217 in a2ebce9

 mode = ClientModeFile 

	if decompressor != nil {
		// ...
		mode = ClientModeFile
	}

Which is why the filename param is not removed, as the next if is skipped, which actually removes the filename param.

go-getter/client.go

Lines 230 to 249 in a2ebce9

 if mode == ClientModeAny { 
 	// Ask the getter which client mode to use 
 	mode, err = g.ClientMode(u) 
 	if err != nil { 
 		return err 
 	} 
  
 	// Destination is the base name of the URL path in "any" mode when 
 	// a file source is detected. 
 	if mode == ClientModeFile { 
 		filename := filepath.Base(u.Path) 
  
 		// Determine if we have a custom file name 
 		if v := q.Get("filename"); v != "" { 
 			// Delete the query parameter if we have it. 
 			q.Del("filename") 
 			u.RawQuery = q.Encode() 
  
 			filename = v 
 		} 

Fix incoming

I fixed it locally and will prepare a pull request soon. Hope you'll like it!