Arrow tips in animated path not always working

[Excentertex]

While testing out the example of the manual (page 398), I noticed that the arrows only show when the code is at the beginning of the document.
To produce the output of the MWE below, I use

latex minimal.tex && dvisvgm --exact minimal.dvi && chromium minimal.svg
Strangely enough, in the MWE only one of the arrow tips disappears.
To produce the correct arrows, simply swap out the tikzpicture environment for the \tikz statement.

Minimal working example (MWE)

\documentclass[dvisvgm]{article}

\usepackage{tikz}
\usetikzlibrary{animations}

\begin{document}

\tikz \node [fill, text=white, animate={
  myself:fill = {0s= "red", 2s="blue", begin on = click }}] {Click me};

% Move this environment to the beginning to produce the correct result
\begin{tikzpicture}
  \draw[help lines] (-2,-2) grid (2,2);
  \draw :path={
  0s="{(0,0) to[out=90,in=180]  (.5 , 1) to [out=0,in=90] (.5,.5)}" base,
  2s="{(1,0) to[out=180,in=180] (.25,.5) to [out=0,in=180] (1,.5)}",
  arrows = <.<->, repeats};
\end{tikzpicture}

\end{document}

[hmenke]

Possible patch, please test.

diff --git a/tex/generic/pgf/systemlayer/pgfsys-common-svg.def b/tex/generic/pgf/systemlayer/pgfsys-common-svg.def
index 6e825f09..f1d27290 100644
--- a/tex/generic/pgf/systemlayer/pgfsys-common-svg.def
+++ b/tex/generic/pgf/systemlayer/pgfsys-common-svg.def
@@ -891,7 +891,7 @@
       \let\pgf@sys@svg@marker@id@start\pgfutil@empty%
     \else%
       \global\advance\pgf@sys@svg@objectcount by1\relax%
-      \edef\pgf@sys@svg@marker@id{pgf\the\pgf@sys@svg@objectcount}%
+      \edef\pgf@sys@svg@marker@id{pgf\the\pgf@sys@svg@objectcount m}%
       \edef\pgf@sys@svg@add@code{%
         \noexpand\pgf@sys@svg@ref@defs{pgfs\pgf@svg@anim@marker@start}%
         \noexpand\pgfsysprotocol@literal{<marker id="\pgf@sys@svg@marker@id" markerUnits="userSpaceOnUse" orient="auto" overflow="visible">
@@ -904,7 +904,7 @@
       \let\pgf@sys@svg@marker@id@end\pgfutil@empty%
     \else%
       \global\advance\pgf@sys@svg@objectcount by1\relax%
-      \edef\pgf@sys@svg@marker@id{pgf\the\pgf@sys@svg@objectcount}%
+      \edef\pgf@sys@svg@marker@id{pgf\the\pgf@sys@svg@objectcount m}%
       \edef\pgf@sys@svg@add@code@{%
         \noexpand\pgf@sys@svg@ref@defs{pgfs\pgf@svg@anim@marker@end}%
         \noexpand\pgfsysprotocol@literal{<marker id="\pgf@sys@svg@marker@id" markerUnits="userSpaceOnUse" orient="auto" overflow="visible">

The underlying problem is that the object ids collide. Both the object and the marker at the start of the path have id='pgf1'.

<g id='pgf1'>
<marker id='pgf1' markerUnits='userSpaceOnUse' orient='auto' overflow='visible'> <use transform='scale(-1,-1)' xlink:href='#pgfs2'/> </marker>
<marker id='pgf2' markerUnits='userSpaceOnUse' orient='auto' overflow='visible'> <use xlink:href='#pgfs3'/> </marker>
<path d='M 0.0 2.27997 C 0.0 12.45241 1.77396 28.45274 14.22636 28.45274 C 19.77419 28.45274 14.22636 19.77419 14.22636 14.68636' fill='none' id='pgf1p' marker-end='url(#pgf2)' marker-start='url(#pgf1)'/>
</g>

The patch works around this collision by just appending the letter m to all marker ids (in the same spirit as paths have the suffix p already).

<g id='pgf1'>
<marker id='pgf1m' markerUnits='userSpaceOnUse' orient='auto' overflow='visible'> <use transform='scale(-1,-1)' xlink:href='#pgfs2'/> </marker>
<marker id='pgf2m' markerUnits='userSpaceOnUse' orient='auto' overflow='visible'> <use xlink:href='#pgfs3'/> </marker>
<path d='M 0.0 2.27997 C 0.0 12.45241 1.77396 28.45274 14.22636 28.45274 C 19.77419 28.45274 14.22636 19.77419 14.22636 14.68636' fill='none' id='pgf1p' marker-end='url(#pgf2m)' marker-start='url(#pgf1m)'/>
</g>

[Excentertex]

I can reproduce your solution!
Thank you for your swift reply.

[hmenke]

This isn't merged yet.