[tex-live] texmf.cnf paths for format files

[Jonathan Kew]

In Master/texmf/web2c/texmf.cnf, we currently have entries such as

TEXFORMATS = .;$TEXMF/web2c/{$engine,}

which means that .fmt files will be found either in the engine- 
specific subdirectory (where fmtutil now places them by default), or  
in the main web2c directory.

However, one issue that remains is that with this setting, naive use  
of kpsewhich will not find the formats:

$ kpsewhich pdftex.fmt
$

It is necessary to use the --engine option, as in:

$ kpsewhich --engine=pdftex pdftex.fmt
/Users/jonathan/.texlive2007/texmf-var/web2c/pdftex/pdftex.fmt
$

This will confuse and frustrate users. Therefore, I propose that we  
add // to the TEXFORMATS, MFBASES, and MPMEMS variables in texmf.cnf,  
e.g.:

TEXFORMATS = .;$TEXMF/web2c/{$engine,}//

Then kpsewhich, with no --engine option, will search subdirectories  
and find the expected format files.

The only case where there's potential confusion with this setting is  
when there are multiple files with the same name in different  
subdirectories of web2c; the ConTeXt formats are the only current  
example where this happens. In this case, kpsewhich finds the pdftex- 
based formats by default (at least for me; is this based on ASCII  
ordering?); if invoked with --engine=xetex, it finds the xetex-based  
version. This seems reasonable behavior.

Comments?

JK