For some reason "doinfo" doesn't have a "newinfo" partner. This is inconsistent since almost all "do*" commands have one.
I think the most common usage case would be something like "newinfo foo foo.info" for packages that come with extensionless info files. See app-emacs/gnus or app-emacs/org-mode for real-life examples.
Let's use this bug as our first for the new way of status tracking.
Let's postpone this until the issues of bug 306445 have been sorted out.
Reopening for proper closing.
Looks like the only clean way to get an info file with a different name is to change the argument of @setfilename in the texinfo source file. Simply renaming the info file may break cross references. Therefore, a "newinfo" command is not a good idea.