Throws an error for urls with branches containing '/'

[eggplantzzz]

When trying to download a url that contains a branch ref with a '/' it throws an error like the following: Error: ENOENT: no such file or directory, open '/Users/.../.../1549913237088-42743833620309557/bare-box-truffle/test-branch.zip'

To duplicate try and use the library to download the following url: https://github.com/truffle-box/bare-box#truffle/test-branch

Is this just a limitation of this package or do you think you will support this in the future?