`make install` broken on windows

[klutzy]

$ ../configure --prefix=/home/it/usr/rust-62f1d68 && make
...

$ make install VERBOSE=1
cfg: build triple i686-pc-mingw32
cfg: host triples i686-pc-mingw32
cfg: target triples i686-pc-mingw32
cfg: enabling more debugging (CFG_ENABLE_DEBUG)
cfg: host for i686-pc-mingw32 is i386
cfg: os for i686-pc-mingw32 is pc-mingw32
cfg: using gcc
cfg: disabling valgrind due to its unreliability on this platform
/home/it/stone/rust-vanilla/mk/stage0.mk:7: warning: overriding recipe for target `i686-pc-mingw32/stage0/bin/'
/home/it/stone/rust-vanilla/mk/stage0.mk:4: warning: ignoring old recipe for target `i686-pc-mingw32/stage0/bin/'
cfg: no pdflatex found, omitting doc/rust.pdf
cfg: no pandoc found, omitting PDF and EPUB docs
cfg: no node found, omitting PDF and EPUB docs
cfg: no llnextgen found, omitting grammar-verification
cfg: including prepare rules
cfg: including install rules
umask 022 && mkdir -p /home/it/usr/rust-62f1d68/bin
umask 022 && mkdir -p /home/it/usr/rust-62f1d68/bin
umask 022 && mkdir -p /home/it/usr/rust-62f1d68/share/man/man1

$ make install VERBOSE=1 --debug
 File `install' does not exist.
   File `prepare-everything' does not exist.
     File `prepare-host' does not exist.
       File `prepare-host-tools' does not exist.
         File `prepare-host-tool-rustdoc-3-i686-pc-mingw32' does not exist.
           File `prepare-host-lib-rustdoc-3-i686-pc-mingw32' does not exist.
             File `prepare-host-lib-rustc-3-i686-pc-mingw32' does not exist.
               File `prepare-host-lib-syntax-3-i686-pc-mingw32' does not exist.
...

[adrientetar]

cc @brson

[klutzy]

workaround: make install PREPARE_STAGES=2

[brson]

Assigning to myself. I'll aim fix it this week, though I wouldn't complain if somebody else did it ahead of me.

[brson]

I've found the problem and will have a patch soon. Basically ISTAGE should be the same as PREPARE_STAGES.