E3-941: Patch CONFIG_SITE after installing EPICS base
If one copies or mounts an e3 installation in a different location than it was built, then INSTALL_LOCATION no longer points at the correct path; this has no real impact on e3 other than producing some spurious error messages that it cannot find convertRelease.pl (which is not necessary for e3).
However, if one were wanting to use this new location for EPICS base in order to build a standard EPICS environment, then issues may arise. The solution is simply to override INSTALL_LOCATION (which must be set correctly when building EPICS base) to that it points to the path of the current installation, as it is mounted.