tikz - place node at absolute position

Question

How can I place node at the intersection of I and C node (I |- C)? MWE:

\documentclass[border=2pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{chains} 
\usetikzlibrary{arrows,chains,positioning,shapes,scopes}

\begin{document}

\begin{tikzpicture}
[>=latex,node distance=.8cm,
start chain =going below,]

\tikzset{base/.style = {
        draw,rounded corners,minimum width=20mm, minimum height=6mm, align=center,
        inner sep=1mm, outer sep=0mm,
        on chain, join=by {->}}}
\tikzset{start/.style={base,minimum size=6mm,circle,fill=black}}
\tikzset{end/.style={base,circle}}
\tikzset{box/.style={base}}
\tikzset{decision/.style={base,rounded corners=0,minimum size=6mm,diamond,aspect=1.5,on chain}}

{
  \node[start] (A) {};
  \node[box] (B) {clone repository};
  \node[box] (C) {coding};
  \node[box] (D) {commit locally};
  \node[box] (E) {review};
  \node[decision] (F) {};
  {[start branch]
      \node[box,left=2cm of F] (G) {rework};
      \node[box,on chain=going above] (H) {recommit};
  }
  {[start branch]
    \node[box,right=2cm of F] (I) {submit};
    \coordinate  (O)  at (I |- C);
    \node[box] at (O) (J)  {update local repository};
  }

\draw[->] (H) -- (E);
\draw[->] (J) -- (C);
% debug code line
\draw[red] (O) -- (I) (O) -- (C);
}
\end{tikzpicture}
\end{document}

The node J should be placed at O but actually not!

Answer 1

Mismatch in placement of node J is caused by on chain properties of box nodes. If you in this cancel this properties, the node will one place where you wish to be.

Since I don't know, if this is possible to do for particular node in chain, I reorganize your tikzset so, that on chain option remove from base and add to box, which is later used in style definition of others nodes' styles.

With this changes and also some changes in connection lines (for which was non logical in your MWE) I obtain the following image:

Is it what you looking for?

\documentclass[tikz, margin=3mm]{standalone}
\usetikzlibrary{chains, shapes}
\begin{document}
    \begin{tikzpicture}[>=latex,
  node distance = 8mm,
    start chain = going below,
    base/.style = {draw, rounded corners,
                   minimum width=20mm, minimum height=6mm, 
                   align=center,
                   inner sep=1mm, outer sep=0mm,
                   },
     box/.style = {base, on chain, join=by {->}},
   start/.style = {box,minimum size=6mm,circle,fill=black},
     end/.style = {box,circle, on chain},
decision/.style = {box, diamond, aspect=1.5, 
                   sharp corners, minimum size=6mm}
                        ]
\node[start] (A) {};
\node[box] (B) {clone repository};
\node[box] (C) {coding};
\node[box] (D) {commit locally};
\node[box] (E) {review};
\node[decision] (F) {};
{%[start branch]
      \node[box,left=2cm of F] (G) {rework};
      \node[box,on chain=going above] (H) {recommit};
  }
  {%[start branch]
    \node[base,
          right=2cm of F] (I) {submit};
    \node[base]  (J)  at (I |- C) {update local repository};
  }

\draw[->] (H) -- (E);
\draw[->] (F) -- (I);
% debug code line
\draw[red,->] (I) edge (J) (J) to (C);
    \end{tikzpicture}
\end{document}