Start Vim with the Proxy Its Vundle Git Children Need

For Vundle updating HTTPS plugin repositories, a POSIX launch can supply the Git children with:

https_proxy=http://proxy.example:8080 vim

Vundle delegates repository work to Git, so this configures the environment inherited by the relevant downloader. For public HTTPS plugin repositories, the HTTP proxy list offers candidate endpoints for that environment value. An already open Vim instance or a desktop launch may have another environment; an export in a separate terminal does not update it.

If Git chooses another route, inspect the scope and source of its applicable http.proxy configuration, which can override the environment. Avoid adding a global setting before checking the scope already in effect.

The repository URL chooses the transport. An HTTP proxy input does not automatically route an SSH URL. Vundle accepts full repository URLs, so use an approved HTTPS URL when that is the intended route.

Keep Git's first error. A proxy-account rejection and repository-access rejection occur at different services and do not call for the same credential change.