PGF outtput differences depending on compiler

Question

Im trying to use this code

\documentclass[margin=5mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc,intersections}

\tikzset{
  anticlockwise arc centered at/.style={
    to path={
      let \p1=(\tikztostart), \p2=(\tikztotarget), \p3=(#1) in
      \pgfextra{
        \pgfmathsetmacro{\anglestart}{atan2(\x1-\x3,\y1-\y3)}
        \pgfmathsetmacro{\angletarget}{atan2(\x2-\x3,\y2-\y3)}
        \pgfmathsetmacro{\angletarget}%
        {\angletarget < \anglestart ? \angletarget+360 : \angletarget}
        \pgfmathsetmacro{\radius}{veclen(\x1-\x3,\y1-\y3)}
      }
      arc(\anglestart:\angletarget:\radius pt) -- (\tikztotarget)
    },
  },
  clockwise arc centered at/.style={
    to path={
      let \p1=(\tikztostart), \p2=(\tikztotarget), \p3=(#1) in
      \pgfextra{
        \pgfmathsetmacro{\anglestart}{atan2(\x1-\x3,\y1-\y3)}
        \pgfmathsetmacro{\angletarget}{atan2(\x2-\x3,\y2-\y3)}
        \pgfmathsetmacro{\angletarget}%
        {\angletarget > \anglestart ? \angletarget - 360 : \angletarget}
        \pgfmathsetmacro{\radius}{veclen(\x1-\x3,\y1-\y3)}
      }
      arc(\anglestart:\angletarget:\radius pt)  -- (\tikztotarget)
    },
  },
}

\begin{document}
\begin{tikzpicture}
  % 3 centers (a, b, c)
  \coordinate (a) at (0,0);
  \coordinate (b) at (-1,-1);
  \coordinate (c) at (1,-1);

  % 3 circles
  \draw[name path=circleA] (a) circle (1.5cm);
  \draw[name path=circleB] (b) circle (1.5cm);
  \draw[name path=circleC] (c) circle (1.5cm);

  % label of circles
  \node (A) at ($(a)+(0,1)$) {$A$};
  \node (B) at ($(b)+(-1,0)$) {$B$};
  \node (C) at ($(c)+(1,0)$) {$C$};

  % intersections of circles (A) and (B)
  \path [name intersections={of=circleA and circleB,name=AB}];
  % show them
  \fill[red] (AB-1) circle (2pt) node[above left] {AB-1};
  \fill[red] (AB-2) circle (2pt) node[below right] {AB-2};

  % intersections of circles (A) and (C)
  \path [name intersections={of=circleA and circleC,name=AC}];
  % show them
  \fill[red] (AC-1) circle (2pt) node[above right] {AC-1};
  \fill[red] (AC-2) circle (2pt) node[below left] {AC-2};

  % intersections of circles (B) and (C)
  \path[name intersections={of=circleB and circleC,name=BC}];
  % show them
  \fill[red] (BC-1) circle (2pt) node[above] {BC-1};
  \fill[red] (BC-2) circle (2pt) node[below] {BC-2};


  \draw[line join=round,orange,fill=orange,fill opacity=.5,line width=1pt]
  (AC-2)
  to[clockwise arc centered at=a] (AB-2)
  to[anticlockwise arc centered at=b] (BC-1)
  to[anticlockwise arc centered at=c] (AC-2);

\end{tikzpicture}
\end{document}

to draw part of a circle. However, when compiling with MikTeX 2.9 or TexLive 2015, the result ends up looking like this instead of this .

Compiling with older versions of TexLive gives the desired output. I assume this is because these old versions don't use pgf 3.0 yet. How can I fix this code to work properly with the new version of pgf?