I haven't studied the internals of that function, but have written my own hashing algo for registration of my software. The main way that you know you can trust it, is that it's open source. Would Satoshi Nakamoto have used it if it had a back door in 2009? I doubt it. Has there been a change since then in github? Hard to get it past anybody if there was anything new introduced because there are too many eyes on it.

I'll be taking a cryptocurrency course with Ivan OnTech starting Feb 1, 2018. I'm relatively new to this field but have been a full time programmer for over 20 years.