Error with fslinstaller.py -- maybe due to renaming

Upon downloading the newest version of FSL, I found that the previous install's fslinstaller.py was still in my download folder, and so my browser created fslinstaller (1).py instead. I ran this, and everything went fine until the very final step, post install tasks, when I got this error:

Performing post install tasks
Traceback (most recent call last):
  File "./fslinstaller (1).py", line 2899, in <module>
    do_install(options, installer_settings)
  File "./fslinstaller (1).py", line 2773, in do_install
    app_links=application_links)
  File "./fslinstaller (1).py", line 2193, in post_install
    install_installer(fsldir)
  File "./fslinstaller (1).py", line 1487, in install_installer
    as_root)
  File "./fslinstaller (1).py", line 571, in copy_file
    raise CopyFileError(str(e))
__main__.CopyFileError: usage: cp [-R [-H | -L | -P]] [-fi | -n] [-apvXc] source_file target_file
       cp [-R [-H | -L | -P]] [-fi | -n] [-apvXc] source_file ... target_directory

I believe it is from this line: https://git.fmrib.ox.ac.uk/fsl/installer/blob/master/src/fslinstaller.py#L1490 At first I thought it was because it was failing to find fslinstaller (1).py, but I now realise that the old fslinstaller.py was indeed there and would have happily been copied in. I gave it root permissions, so I don't know why this failed. (And I deleted the install and tried it again, and got the same error). The install seems fine, but just wanted to report the experience.

(MacOS Mojave).