[tex-live] small bug re installing x86_64-darwin vs. universal-darwin

[Richard Koch]

Folks,

When we first created 64 bit binaries for the Mac, I wanted to make
the jobs of the TeX Live folks as easy as possible. Although I requested
that x86_64-darwin binaries be added, I said there was no
reason to modify the tex live install script. Therefore users who
install with that script get universal-darwin binaries by default.

Users who install with MacTeX get BOTH sets of binaries, and then
tlmgr does the right thing to keep them both up to date.
The decision about which binaries to activate is made by MacTeX
and the TeX Dist Control Pane, based on the user's current
operating system and hardware.

I'm in Seattle and haven't been following the discussion as closely
as I should. It sounds like Mojca has discovered cases when this
decision causes problems. Mojca and I will privately discuss the 
issue when I'm back in Eugene and report back.

I have one qualm about modifying the install script.
An advantage of having both universal
binaries and 64 bit binaries is that we can compile the 64 bit versions
on recent machines and still support older machines with the universal
binaries. Right now we compile the 64 bit binaries on Snow Leopard.
In the future we might want to compile on, say, Mountain Lion using
llvm and clang rather than gcc. Such a change is now easy because
only MacTeX and the Preference Pane need to be aware of the new
requirements for 64 bit binaries. Adding TeX Live scripts
to that list risks making mistakes. 

Dick Koch