Bundler should not call which under windows

[arthurschreiber]

Windows does normally not provide a which command, so there is no point in calling this on Ruby running on windows.

Actually, this can even cause problems, when there is a which.exe in your path that does not do what *nix which does. In fact, this causes problems when running bundler on the windows servers im deploying to, as calling which there is a) sloooow, and b) raises an error.

One such occurrence of calling which is in Bundler.requires_sudo?, which shouldn't even have to check for sudo when running on windows.

[dmag]

also, in "requires_sudo?" Bundler tries to figure out where the sudo binary is -- even if it decides it doesn't need sudo. So it ends up running sh which sudo four times. This wouldn't be so bad for "bundle ..." commands, but it does this for EVERY ruby script that loads bundler. Can we defer which sudo for the times we actually need it?