[exim-dev] warning on missing environment option

Hello,

I am a little bit unhappy with the current state of
add_environment/keep_environment:

* Exim throws a runtime warning if neither of the options is set.
* configure.default does not set either of the options
(even f26587cbf325ebb365cd670db767363775391dc6 has only commented
examples).
* Setting keep_environment to an empty value ("keep_environment =")
makes the warning go away, doing the same for add_environment doesn't.

All this seems to be incongruent. The warning suggests that all but very
atypical installation will want to set at least one of the environment
options. But we are not able to come up with a a sane, safe default that
is set in our configuration example. (If there was a sane safe default
keep_environment would use this instead of "" by default and we would
not need to set it explicitely everywhere, and the warning would be
superfluous.)

I am personally wondering whether the warning is really necessary lor
too invasive. In Debian I have set "add_environment = <;
PATH=/bin:/usr/bin" for lack of a better idea and because my experiment
with "add_environment =" failed to suppress the warning. If I started
fresh now I'd set "keep_environment =" instead.

The third issue mentioned above ("add_environment =" does not suppress
a warning) seems to be a bug as it is not documented.

cu Andreas
--
`What a good friend you are to him, Dr. Maturin. His other friends are
so grateful to you.'
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