UploadSpec directory structure behaviour change

Specs deploy artifacts with only partial path.
For example when using the spec below the file "build-output/a.txt" should be uploaded to "repo-name/subdir/build-output/a.txt" but being uploaded to "repo-name/subdir/a.txt"

{
  "files": [
    {
     "regexp": "false",
     "flat": "false",
     "pattern": "build-output/*",
     "target": "repo-name/subdir/",
    }
  ]
}