emcc.bat prints out extra lines if emsdk is installed in path with spaces (HostOS: Windows)

[aportale]

When executing emcc.bat -dumpversion, I would usually just get an output with a version number. If emsdk is installed in a path that contains spaces, I get more output than expected.

Version of emscripten/emsdk:
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.50 (047b825)
clang version 18.0.0 (https://github.com/llvm/llvm-project 14028ec0a62210d68a4dd7a046ac79c8c3b7727e)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: C:\Users\alportal\path with spaces\emsdk\upstream\bin

Failing command line in full:
emcc.bat -dumpversion

If emsdk is installed within a path that contains spaces, the output contains extra lines:

c:\Users\alportal\path with spaces\emsdk>set MYDIR=C:\Users\alportal\path with spaces\emsdk\upstream\emscripten\

c:\Users\alportal\path with spaces\emsdk>goto FOUND_MYDIR
3.1.50

This extra output of the compiler can cause issues, like for example in the Qt Creator IDE: QTCREATORBUG-29758 QTCREATORBUG-29981

[sbc100]

Man.. what a strange bug. I found a fix but I have no idea why it works: #20916