@GossiTheDog @faebudo @FritzAdalis @jernej__s
If I remember my testing properly, a junction to a folder does not break the update. But a weird junction to a file (which Microsoft claims is not possible) does break the April update.
Which mirrors the test that a C:\inetpub directory does not break the update but a C:\inetpub file does break things. Except that the junction variant is something a non-admin user can do.