Fix '.search also' with /handler config=full or existing

Make .expand* handlers use relative paths if the original path was relative.
Fixes pgf-tikz#1143

Author: fritzw

tex/generic/pgf/utilities/pgfkeys.code.tex

@@ -1006,7 +1006,13 @@
 \pgfkeys{/handlers/.expand twice/.code=\expandafter\expandafter\expandafter\pgfkeys@exp@call\expandafter\expandafter\expandafter{#1}}
 \pgfkeys{/handlers/.expanded/.code=\edef\pgfkeys@temp{#1}\expandafter\pgfkeys@exp@call\expandafter{\pgfkeys@temp}}
 
-\long\def\pgfkeys@exp@call#1{\pgfkeysalso{\pgfkeyscurrentpath={#1}}}
+\long\def\pgfkeys@exp@call#1{%
+  \ifpgfkeysaddeddefaultpath% If the original key was a relative path, do the expanded assignment with a relative path as well.
+    \pgfkeys@pathtoks{}%
+    \expandafter\pgfkeys@splitter\pgfkeyscurrentkeyRAW//% Removes the /.expand* component of the original relative key.
+  \fi
+  \pgfkeysalso{\pgfkeyscurrentpath={#1}}%
+}
 
 \def\pgfkeys@mathparse{%
   \pgfkeys@ifcsname{pgfmathparse}{%