Skip startup check

[cstjean]

I'm working in a secured environment. juliaup worked fine, so does julia, but sudo julia fails with:

Checking for new Julia versions
Error: Failed to run `run_command_add` from the `run_command_initial_setup_from_launcher` command.

Caused by:
    0: Failed to update versions db.
    1: Failed to download current version db version.
    2: Failed to download from url `https://julialang-s3.julialang.org/juliaup/RELEASECHANNELDBVERSION`.
    3: error sending request for url (https://julialang-s3.julialang.org/juliaup/RELEASECHANNELDBVERSION)
    4: operation timed out
Error: The Julia launcher failed to figure out which juliaup channel to use.

Obviously, I can spend a week negociating with BigCo's IT department to fix the underlying issue, but I'd appreciate a shorter work-around. Is there any way to skip that check? Or to run the non-juliaup'ed julia binary directly?

Related: #705.