I seriously wonder why there is an ncurses4 package and not just a couple of symlinks and an provides libncurses.so.4. Esp since the only change is the .so version, no api changes we're made so I seriously wonder what the use is of this seperate package. Also libforms and the other companionlibs for ncurses are missing in the ncurses4 package.
This is intentional. There have been no API changes, but there has been a minor ABI change. It probably doesn't affect anything because it only affects a function I've never seen used anywhere, but better safe than sorry. We aren't including libforms and libmenu because we never shipped anything that uses them.
If there has been an ABI change, then the ncurses4 package is justified, I however can't find anything about this in the changelog for ncurses5, and it seems strange that there is an ABI incompatibility, since for other distros the major .so number won't change if they upgrade to this build ?!