Error when /.lastretry fails

[schtandard]

This code

\documentclass{article}

\usepackage{pgfkeys}

\begin{document}

%\pgfkeys{/a/.code=(a:#1)}
%\pgfkeys{/b/.code=(b:#1)}

\pgfkeys{/a/.try=one,/b/.lastretry=two}

\ifpgfkeyssuccess Yes\else No\fi

\end{document}

leads to this error

(test03.aux)
Runaway argument?
\relax \pgfkeys@unknown \fi \fi \else \pgfkeys@unknown \fi \fi \fi \fi \ETC.
! Paragraph ended before \pgfkeys@remove@slash was complete.
<to be read again> 
				   \par 
l.12 

(If either of the commented \pgfkeys lines is uncommented, or if lastretry is replaced with retry, there is no error, as expected.)