The source committed to SVN was for earlier PFS3 version (iirc PFS3 5.2 aka 18.4)
Well, you might wanna bring RELNUM up-to-date. Currently it's still at 5.0.
The SVN "trunk" version is work in progress (and as such the revision hasn't been touched yet). The SVN trunk version isn't guaranteed to be stable at any given moment. Obviously there's nothing we can do to prevent anyone from releasing snapshot builds, but I would appreciate it if any such release would be accompanied with a warning about it being only a snapshot build.
So why not add an alpha or beta definition in the svn, like #define RELNUM "5.2 Beta" (or Alpha), which I did in my copy (unreleased though).