On my system (openSUSE 12.2 / GNU bash, version 4.2.24(1)-release (x86_64-suse-linux-gnu) ), the shell doesn't like that the '=' character in 'if test...' doesn't have spaces around it. This causes the test to always be true, and thus the AS_AC_EXPAND macro only expands once. This led to two #define's in config.h containing broken values: HEXCHATSHAREDIR and DBUS_SERVICES_DIR.

acinclude.m4

@@ -26,7 +26,7 @@ AC_DEFUN([AS_AC_EXPAND],
   dnl loop until it doesn't change anymore
   while true; do
     new_full_var="`eval echo $full_var`"
-    if test "x$new_full_var"="x$full_var"; then break; fi
+    if test "x$new_full_var" = "x$full_var"; then break; fi
     full_var=$new_full_var
   done
 

configure.in

@@ -592,9 +592,8 @@ if test "x$dbus" = "xyes" ; then
 		COMMON_LIBS="$COMMON_LIBS $DBUS_LIBS"
 		COMMON_CFLAGS="$COMMON_CFLAGS $DBUS_CFLAGS"
 		AC_DEFINE(USE_DBUS)
-		AS_AC_EXPAND(DATADIR, $datadir)
 
-		DBUS_SERVICES_DIR="$DATADIR/dbus-1/services"
+		AS_AC_EXPAND(DBUS_SERVICES_DIR, "$datadir/dbus-1/services")
 		AC_SUBST(DBUS_SERVICES_DIR)
 		AC_DEFINE_UNQUOTED(DBUS_SERVICES_DIR, "$DBUS_SERVICES_DIR", [Where services dir for DBUS is])
 	fi
@@ -911,10 +910,10 @@ test "x$exec_prefix" = xNONE && exec_prefix="$prefix"
 
 AC_DEFINE_UNQUOTED(PREFIX, "${prefix}")
 
-HEXCHATLIBDIR=`eval echo ${libdir}/hexchat`
+AS_AC_EXPAND(HEXCHATLIBDIR, "${libdir}/hexchat")
 AC_DEFINE_UNQUOTED(HEXCHATLIBDIR, "$HEXCHATLIBDIR")
 
-HEXCHATSHAREDIR=`eval echo ${datadir}`
+AS_AC_EXPAND(HEXCHATSHAREDIR, "$datadir")
 AC_DEFINE_UNQUOTED(HEXCHATSHAREDIR, "$HEXCHATSHAREDIR")
 
 dnl for plugins/xxx/Makefile.am