[tex-live] Fatal format file error; I'm stymied

[Karl Berry]

    export TEXMFVAR=

unset TEXMFVAR would be much better.  (Or, if we're talking about an
initialization file, just refrain from setting it at all.)

An envvar whose value is the empty string is very different (and
unusual) from an envvar which is not set at all.  Although we've tried
to make many of our programs treat them as equivalent, for convenience,
I'm sure there are plenty of cases left where they are not.

Best,
k