Brackets are removed by autoconf leading to invalid syntax in configure.

--- hplip-3.25.6/configure.in.orig
+++ hplip-3.25.6/configure.in
@@ -632,12 +632,12 @@
 
 SAVE_CPPFLAGS="$CPPFLAGS"
 CFLAGS=`python-config --includes`
-if [ $? -eq 0 ] 
+if test $? -eq 0
 then
    echo $FLAGS
 else
 CFLAGS=`python3-config --includes`
-   if [ $? -eq 0 ]
+   if test $? -eq 0
    then
    echo $FLAGS
    fi