Broken physics.sty after today's MiKTeX update, how to fix?

Question

After the latest MiKTeX update, I started getting "Missing delimiter (. inserted)." errors on places where I've never had such before. A somewhat minimal .tex file points the problem to physics.sty. Here is it:

\documentclass[11pt,a4paper,twoside]{report} 
\usepackage{geometry}
\geometry{a4paper,left=40pt,right=40pt,top=45pt,bottom=40pt}

% Bibliography/References:
\usepackage[nottoc]{tocbibind} % puts bibliography in ToC
\bibliographystyle{amsalpha}

% Language settings for special characters:
\usepackage[utf8]{inputenc}

% enumeration and items:
\usepackage[shortlabels]{enumitem}

% page numbering:
\setenumerate{label={\normalfont(\arabic*)}}

% mathematical packages:
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsthm} 
\usepackage{physics} 
\usepackage{latexsym}
\usepackage{mathtools} 
\usepackage{mathrsfs} % additional caligraphic font for math
\usepackage{tikz-cd} % for commutative diagrams
\usetikzlibrary{arrows}
\tikzcdset{arrow style=tikz,>=angle 60} 

\begin{document}
    \begin{equation}\label{exp}
        \exp(T)=\sum_{k=0}^\infty \frac{T^k}{k!}\in K[[T]]
    \end{equation}
\end{document}

This produces the error:

physics.sty error line 34: Missing delimiter (. inserted). \exp(T)
physics.sty error line 34: Missing delimiter (. inserted). \exp(T)

How do I fix this?

Thanks!

EDIT: Here is the entire log: http://pastebin.com/S80vDD7J

Answer 1

This is caused by some changes in xparse, used by physics. Essentailly, physics (and some other packages) have used 'document commands' in a way that the team did not expect (nor intend to support). We will be issuing an xparse update shortly to fix the issue whilst we decide on a long-term policy. Once that happens it's likely that the team will explicitly rule out certain use cases, at which point physics will need an update.