First of all I installed the latest public version, which displayed 3.0.1.6 in the "powered by" footer. The SVN version says 3.0.1.4 in config.inc.php. I packaged my working copy, downloaded it onto the server, and used update.php to update the server install, and now it shows 3.0.1.5 as the version. I haven't checked the update script yet, but something isn't going right somewhere. I was originally going to set the version to 3.0.1.6 in config.inc.php but I now know that would make no difference when doing an update. Edit: Just gone through the update scripts and found the config master file, so have updated the version in there and in the interface/lib dir and will commit change once I've tested it.
I guess you did not install the software or copied over the config.inc.php file manually from svn to a installed system. The version number in config.inc.php is set by the installer at install time or during an update (the complete file gets replaced by the template from the inatsll/tpl folder), the version number that is in the dummy placeholder file in the lib directory in SVN does not matter.
I didn't copy any files over manually, I just ran the update script. install/tpl/config.inc.php.master was set to 3.0.1.5 which explains why that was showing in the web interface after the install. I changed the version in this file to 3.0.1.6 and ran the update again and it now shows the correct version