When setting an environment variable like C_INCLUDE_PATH to something like "/dev/env/XXX/include" the current version of djgpp.env will convert it to lower case and subsequently the variable 'xxx' (now lower case) will not be found.

Obvious workaround is to remove the lower case conversion operator ('>') in djgpp.env, but I'd prefer djgpp to accept lower case env variable names.

Case-sensitive environment variables are a feature of DOS.  I don't think we
should break that feature (by converting all variables to a single case) just
because of this marginal situation.  Such a change will certainly break some
code out there.

So I don't think that making enviroenment variables case-insensitive is a
good idea.

One obvious work-around (or even a solution?) would be not to use /dev/env
in environment variables.  There should be no need for this: you could simply
say %FOO% instead of /dev/env/FOO.  

/dev/env exists to pacify programs that hard-code file names into the binaries
when they are built; using /dev/env/FOO defers the environment variable
expansion till run time, instead of having the file names from the build
machine, which might not work on other machines.