Reinsert the last token when giving up on a path pgf-tikz#1025

Cherry-pick hmenke@8a6c14c

tex/generic/pgf/frontendlayer/tikz/tikz.code.tex

@@ -2437,6 +2437,16 @@
   \endgroup%
   \global\pgflinewidth=\tikzscope@linewidth%
   \tikz@path@do@at@end%
+  %
+  % Optional step: Reinsert last token
+  %
+  % If there was an error, then \tikz@finish was called to give up on the
+  % path. Since we do not know whether the error was caused by a misspelled
+  % keyword or due to expansion, we reinsert the previously collected token here.
+  %
+  \expandafter\let\expandafter\tikz@expand@last@token@\csname tikz@expand@last@token\endcsname
+  \global\let\tikz@expand@last@token=\relax
+  \tikz@expand@last@token@
 }%
 \let\tikz@lib@scope@check\pgfutil@empty% this is a hook for the scopes library
 \def\tikz@path@do@at@end{\tikz@lib@scope@check}%
@@ -2487,6 +2497,8 @@
   \advance\tikz@expandcount by -1
   \ifnum\tikz@expandcount<0\relax%
     \tikzerror{Giving up on this path. Did you forget a semicolon?}%
+    % since the last token caused an error we should reinsert it and therefore save it
+    \global\let\tikz@expand@last@token=\pgf@let@token
     \let\pgfutil@next=\tikz@finish%
   \else%
     \let\pgfutil@next=\tikz@@expand