when "mod_gzip_on yes", PHP's force-cgi-redirect security mechanizm becomes disabled (urls like /cgi-bin/php/test.php start working) and PHP_SELF takes on a wrong value (/cgi-bin/php/test.php).
when "mod_gzip_on no", both aspects of the problem disappear.
problem has been observed on 2 different systems.
apache version: 1.3.26, 1.3.27
php version: latest snapshot
mod_gzip version: latest
php.ini does not exist.
php's configure:
./configure \
        --with-config-file-path=/path/to/php \
        --prefix=/path/to/php \
        --enable-force-cgi-redirect \
        --disable-cli \
        --enable-bcmath \
        --enable-trans-sid \
        --with-zlib-dir=/build/zlib-1.1.4 \
        --with-gd=/build/gd-1.8.4 \
        --with-png-dir=/build/png-1.2.4 \
        --with-jpeg-dir=/build/jpeg-6b \
        --with-freetype \

apache's configure:
./configure \
        --prefix=/path/to/apache \
        --enable-module=so \
        --enable-suexec \
        --suexec-caller=www \
        --suexec-docroot=/www \
no other modules loaded other than mod_gzip.
i thought this could well be PHP's problem. sorry if i'm wrong, then please direct me to other possible sources of the problem.