/bin/sh doesn't run autoconf'ied configure scripts correctly

I'm running 6.1-BETA1, and I guess this is a part of the 27,000 
regressions that happened from 5.4 to 6.1, however, when using sh as the 
bourne code interpreter, configure scripts fail to execute. It's not a 
guaranteed  thing, as it happens randomly. Upon using the SVN code from 
Audacious media player (it builds on NetBSD, OpenBSD, Linux, etc.), 
here's what happens:

[kash_at_rama ~/src/audacious-devel]$ sh autogen.sh
*info* running autopoint (-f)
*info* running libtoolize (-f -c)
*info* running aclocal19 (-I /usr/local/share/aclocal -I m4)
/usr/X11R6/share/aclocal/xmms.m4:17: warning: underquoted definition of 
XMMS_TEST_VERSION
  run info '(automake)Extending aclocal'
  or see http://sources.redhat.com/automake/automake.html#Extending-aclocal
/usr/X11R6/share/aclocal/xmms.m4:62: warning: underquoted definition of 
AM_PATH_XMMS
/usr/X11R6/share/aclocal/gtk.m4:7: warning: underquoted definition of 
AM_PATH_GTK
/usr/X11R6/share/aclocal/gdk-pixbuf.m4:12: warning: underquoted 
definition of AM_PATH_GDK_PIXBUF
/usr/local/share/aclocal/speex.m4:10: warning: underquoted definition of 
XIPH_PATH_SPEEX
/usr/local/share/aclocal/linc.m4:1: warning: underquoted definition of 
AM_PATH_LINC
/usr/local/share/aclocal/libmikmod.m4:11: warning: underquoted 
definition of AM_PATH_LIBMIKMOD
/usr/local/share/aclocal/libfame.m4:6: warning: underquoted definition 
of AM_PATH_LIBFAME
/usr/local/share/aclocal/glib.m4:8: warning: underquoted definition of 
AM_PATH_GLIB
/usr/local/share/aclocal/audiofile.m4:12: warning: underquoted 
definition of AM_PATH_AUDIOFILE
/usr/local/share/aclocal/ao.m4:9: warning: underquoted definition of 
XIPH_PATH_AO
/usr/local/share/aclocal/aalib.m4:12: warning: underquoted definition of 
AM_PATH_AALIB
*info* running autoheader259
*info* running autoconf259
*info* running automake19 (-a -c)
Plugins/Output/jack/Makefile.am: installing `./depcomp'

It created the configure script, but when I run it, it ignores all 
switches, and makes bogus makefiles. gmake fails miserably as well.

[kash_at_rama ~/src/audacious-devel]$ ./configure --help
configure: WARNING: you should use --build, --host, --target
checking build system type... amd64-unknown-freebsd6.1
checking host system type... amd64-unknown-freebsd6.1
checking target system type... amd64-unknown-freebsd6.1
checking for a BSD-compatible install... /usr/bin/install -c

[kash_at_rama ~/src/audacious-devel]$ gmake
[building subobjective: Plugins]
[building subobjective: Input]
[building subobjective: cdaudio]
[building library objective: libcdaudio.so]
make: don't know how to make s. Stop
      LINK     libcdaudio.so      
gcc: cdaudio.o: No such file or directory
gcc: cddb.o: No such file or directory
gcc: cdinfo.o: No such file or directory
gcc: configure.o: No such file or directory
gcc: http.o: No such file or directory
gmake[4]: *** [libcdaudio.so] Error 1
[finished library objective: libcdaudio.so]
[all objectives built]
[finished subobjective: cdaudio]
[building subobjective: tonegen]
[building library objective: libtonegen.so]
make: don't know how to make s. Stop
      LINK     libtonegen.so      
gcc: tonegen.o: No such file or directory
gmake[4]: *** [libtonegen.so] Error 1
[finished library objective: libtonegen.so]
[all objectives built]
[finished subobjective: tonegen]
[building subobjective: console]
[building library objective: libconsole.so]
make: don't know how to make s. Stop
      LINK     libconsole.so      
gcc: Blip_Buffer.o: No such file or directory
gcc: Classic_Emu.o: No such file or directory
gcc: Dual_Resampler.o: No such file or directory
gcc: Fir_Resampler.o: No such file or directory
gcc: Gb_Apu.o: No such file or directory
gcc: Gb_Cpu.o: No such file or directory
gcc: Gb_Oscs.o: No such file or directory
gcc: Gbs_Emu.o: No such file or directory
gcc: Gym_Emu.o: No such file or directory
gcc: Multi_Buffer.o: No such file or directory
gcc: Music_Emu.o: No such file or directory
gcc: Nes_Apu.o: No such file or directory
gcc: Nes_Cpu.o: No such file or directory
gcc: Nes_Fme7_Apu.o: No such file or directory
gcc: Nes_Namco_Apu.o: No such file or directory
gcc: Nes_Oscs.o: No such file or directory
gcc: Nes_Vrc6_Apu.o: No such file or directory
gcc: Nsfe_Emu.o: No such file or directory
gcc: Nsf_Emu.o: No such file or directory
gcc: Sms_Apu.o: No such file or directory
gcc: Snes_Spc.o: No such file or directory
gcc: Spc_Cpu.o: No such file or directory
gcc: Spc_Dsp.o: No such file or directory
gcc: Spc_Emu.o: No such file or directory
gcc: Vgm_Emu.o: No such file or directory
gcc: abstract_file.o: No such file or directory
gcc: Vfs_File.o: No such file or directory
gcc: Gzip_File.o: No such file or directory
gcc: Vgm_Emu_Impl.o: No such file or directory
gcc: Ym2413_Emu.o: No such file or directory
gcc: Ym2612_Emu.o: No such file or directory
gcc: Track_Emu.o: No such file or directory
gcc: Audacious_Driver.o: No such file or directory
gmake[4]: *** [libconsole.so] Error 1
[finished library objective: libconsole.so]
[all objectives built]
[finished subobjective: console]
[building subobjective: sexypsf]
[building library objective: libsexypsf.so]
make: don't know how to make s. Stop
      LINK     libsexypsf.so      
gcc: PsxBios.o: No such file or directory
gcc: PsxCounters.o: No such file or directory
gcc: PsxDma.o: No such file or directory
gcc: Spu.o: No such file or directory
gcc: PsxMem.o: No such file or directory
gcc: PsxHw.o: No such file or directory
gcc: Misc.o: No such file or directory
gcc: R3000A.o: No such file or directory
gcc: PsxInterpreter.o: No such file or directory
gcc: PsxHLE.o: No such file or directory
gcc: spu/spu.o: No such file or directory
gcc: xmms.o: No such file or directory
gmake[4]: *** [libsexypsf.so] Error 1
[finished library objective: libsexypsf.so]
[all objectives built]
[finished subobjective: sexypsf]
[building subobjective: wav]
[building library objective: libwav.so]
make: don't know how to make s. Stop
      LINK     libwav.so          
gcc: wav.o: No such file or directory
gmake[4]: *** [libwav.so] Error 1
[finished library objective: libwav.so]
[all objectives built]
[finished subobjective: wav]
[building subobjective: mpg123]
[building library objective: libmpg123.so]
make: don't know how to make s. Stop
      LINK     libmpg123.so       
gcc: mpg123.o: No such file or directory
gcc: configure.o: No such file or directory
gcc: fileinfo.o: No such file or directory
gcc: common.o: No such file or directory
gcc: decode_2to1.o: No such file or directory
gcc: decode_4to1.o: No such file or directory
gcc: layer1.o: No such file or directory
gcc: layer2.o: No such file or directory
gcc: layer3.o: No such file or directory
gcc: tabinit.o: No such file or directory
gcc: equalizer.o: No such file or directory
gcc: http.o: No such file or directory
gcc: dxhead.o: No such file or directory
gcc: id3.o: No such file or directory
gcc: id3_frame.o: No such file or directory
gcc: id3_frame_content.o: No such file or directory
gcc: id3_frame_text.o: No such file or directory
gcc: id3_frame_url.o: No such file or directory
gcc: id3_tag.o: No such file or directory
gcc: decode.o: No such file or directory
gcc: dct64.o: No such file or directory
gmake[4]: *** [libmpg123.so] Error 1
[finished library objective: libmpg123.so]
^Cgmake[2]: *** [build] Interrupt: 2
gmake[1]: *** [build] Interrupt: 2
gmake: *** [build] Interrupt: 2