HTTP: Don't attempt to needlessly decompress redirect body

This change fixes a regression where redirect body would needlessly be
decompressed even though it was to be ignored anyway. As it happens this
causes secondary issues since there appears to be a bug in apache2 that
it in certain conditions generates a corrupt zlib response. The
regression was created by commit:
dbcced8e

Discovered-by: Harry Sintonen
Closes #2798