tools/upgrade --server_only option

[Eric Myers]

Right now the tools/upgrade script has a --web_only option to allow projects to upgrade just the web server code, leaving the project server stuff in place. This makes it easier to upgrade when a problem crops up (eg security issue) without worrying about custom changes to the server configuration.

I suggest there should also be a --server_only option to just upgrade the server components, leaving the web stuff alone. This would make it easier for projects to upgrade when there are problems with server code (eg. recent RPC vulnerability) without worrying about having to make changes to the PHP server code.

Note also that --web_only updates the python stuff, which might properly be considered "server" stuff rather than "web" stuff. But I don't know if it would break anything to not update the python stuff for --web_only.

[davea]

(In [20052]) - upgrade: add --server_only option

(updates scheduler and back-end programs, but not web code) fixes #968