Hey,
This problem seems to be related to how git bash deals with paths, you can find more about this issue here: https://github.com/angular/angular-cli/issues/5606.
We will investigate a solution to deal with this problem.
As workaround you can invoke run your application like this:
MSYS2_ARG_CONV_EXCL="--base-href;--deploy-url" node_modules/angular-ide/bin/ng serve --proxy-config proxy.conf.local.js --environment=local --dev --port=4201 --base-href=/sos/ --deploy-url=/sos/
Or to use with a script named local:
MSYS2_ARG_CONV_EXCL="--base-href;--deploy-url" npm run local -- --base-href=/sos/ --deploy-url=/sos/
Let us know how it works.
Cheers,
Sal