UE4 installs to a folder titled UE_4.xx....why is that?

If you have a list of version numbers, can’t you just create that list with the correct names?

make:
[FONT=Courier New]UE_VERSIONS := 4.12 4.13 4.14 UE_4.15

scons:
[FONT=Courier New]UE_VERSION = “4.12”, “4.13”, “4.14”, “UE_4.15” ]

and so on …