[pretest, installer]: Broken pipe error when trying to change TEXDIR

[Uwe Siart]

I'm on win10. There I run install-tl-windows.bat with admin privileges
from a local repository (rsynced from cstug).

When I try to change TEXDIR in the GUI I get "error writing file ...
broken pipe" after clicking the button. However, changing TEXMFLOCAL
works (gives me a prompt window to enter my changes and also saves my
changes).

-- 
Uwe