Possibly inconsistent install/lookup behavior in the presence of CHICKEN_INSTALL_PREFIX

[Mario Domenech Goulart]

The title is very poor and the description is going to be a paste of the discussion in #chicken.

Basically, the issue is highlighted by one of the tests of srfi-29

        -- testing Installed Test Bundle -------------------------------------
        (localized-template/default 'srfi-29 'srfi-29) ............... [ FAIL]
            expected "SRFI 29" but got srfi-29

Discussion in #chicken:

<mario-goulart> klovett: apparently srfi-29 is installing the srfi-29
                bundle via the `data' section in the .egg file.  That
                makes the bundle be installed under
                PREFIX/share/chicken when CHICKEN_INSTALL_PREFIX is
                *unset*.  When CHICKEN_INSTALL_PREFIX *is set* (that's
                what salmonella does), the srfi-29 bundle is installed
                under PREFIX/share (no chicken directory).
<mario-goulart> Then srfi-29 looks for bundles under include-path,
                which resolves to C_INSTALL_SHARE_HOME when
                CHICKEN_INCLUDE_PATH is *unset*.  In that case,
                PREFIX/share/$(PROGRAM_PREFIX)chicken$(PROGRAM_SUFFIX). However
                when CHICKEN_INCLUDE_PATH *is set*, chicken-install
                installs the bundle under PREFIX/share, but in runtime
                it looks for bundles under include-path, which is the
                value of CHICKEN_INCLUDE_PATH, which is set by
                salmonella as PREFIX/share/chicken.
<Bunny351> hm...
<mario-goulart> Now I don't know if salmonella is setting
                CHICKEN_INCLUDE_PATH wrongly of if the default values
                given to override-prefix in egg-compile.scm is wrong.
<Bunny351> possible
<mario-goulart> The default values given to override-prefix definitely
                don't match the values of C_INSTALL_INCLUDE_HOME and
                C_INSTALL_SHARE_HOME.
<klovett> originally it only looked in (chicken-home)
<mario-goulart> I think that was the same as what now (include-path)
                is, if I'm not mistaken.
<klovett> well, one is a set
<mario-goulart> I _think_ (don't quote me on that) the root cause of
                the issue is the inconsistency between the values of
                C_INSTALL_INCLUDE_HOME/C_INSTALL_SHARE_HOME and the
                way that override-prefix assembles paths when when
                CHICKEN_INSTALL_PREFIX is set.
<klovett> is something is chicken.platform returning PREFIX/share? i
          can code the envvar test & subsequent path assumption but
          rather not.
<mario-goulart> That's part of the problem I'm implying.  You can get
                PREFIX/share *if* CHICKEN_INCLUDE_PATH is set to
                PREFIX/share.  If CHICKEN_INCLUDE_PATH is *not set*
                you'll get PREFIX/share/chicken (or, more accurately,
                PREFIX/share/$(PROGRAM_PREFIX)chicken$(PROGRAM_SUFFIX)).
<mario-goulart> This whole thing is very confusing.
<klovett> there is not a '(data-path)' so i will assume if
          CHICKEN_INSTALL_PREFIX is set then push "...PREFIX/share"
          onto the search list
<mario-goulart> I think it would be better to wait a bit.  I _think_
                srfi-29 is probably doing the right thing.  The issue
                _might_ be in salmonella or in CHICKEN.
<klovett> ok
<klovett> looks like a job for chicken.platform#data-repository or similar