The answer to this question Using
makecert for Development SSL fixed this for me.
I do not know why, but the certificate created by the simple 'Create
Self Signed Certificate' link in IIS Manager does not do the trick. I
followed the approach in 496658 of creating and installing a self-signed CA
Root; then using that to issue a Server Authentication Certificate for my
server. I installed both of them in IIS.
That gets my situation the same as the blog post referenced in the Q.
Once the root certificate was copy/pasted into curl-ca-bundle.crt the
git/curl combo were satisfied.