/usr/bin/start shell script should be replaced with a native windows executable

/usr/bin/start has this line:

cmd //c start "${@//&/^&}"

The double slash prevents conversion of /c into C:\, instead it's converted to /c with a single slash. I couldn't find this info at https://www.msys2.org/docs/filesystem-paths/ though.

I expect that this tool will accept the command line arguments, perform the needed path conversions and launch cmd /c start ...

However, MSYS2_ARG_CONV_EXCL=* or MSYS2_ARG_CONV_EXCL=// affect both the actual arguments and //c. This variable should only affect the actual arguments and I see only one way to do that: replace the script with a native windows executable. Then MSYS2 will pass some command line to that executable with already converted paths and it can run cmd /c without a problem.

I personally do export MSYS2_ARG_CONV_EXCL='*' in my "git for windows" installation and this breaks git help: starts an interactive cmd prompt instead of launching the browser.

Start by reading /usr/bin/start and the issue's description of MSYS2_ARG_CONV_EXCL, then verify how //c and user arguments are converted. Done means a native Windows executable accepts the arguments, preserves the intended path conversion behavior, invokes cmd /c start, and no longer breaks git help when exclusion is set.