In the case of building subversion and httpd from source, and the current release of httpd is 2.2.x, the apr-1 library should be preferred in the subversion build. The idea is to make the configure script smarter if both apr-0 and apr-1 are detected in the PATH. apr-1 should always be first choice. That would save some headache of package maintainers. When they migrate from apache 2.0.x to 2.2.x, the incompatible apr-0 instead of apr-1 might lead to a segfault/bus error later at runtime, which is not easy to track down.
Original issue reported by jprante