copy(src, dst) fails with EACCES when copying a read-only directory with content on MacOS

[mbargiel]

Copying a directory using the recursive copy function fails with permission error on MacOS if the target is (or contains) a read-only directory with contents.

Repro steps:

1. Create the following hierarchy:

root
|- file
\- subdir
   \- nested_file

2. Make all files and folders read-only
3. Run the following node snippet:

const fse = require('fs-extra')
fse.copy('root', 'target')

• Expected: success
• Actual: the target directory is created but it is empty, and the following is printed: (node:5199) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: EACCES: permission denied, open 'target/file'

• Operating System: Mac OS 10.13.5
• fs-extra version: 6.0.1