configure: add ability to force python version via environment

This is makes it a bit easier to run our test suite under alternative
python versions.

diff --git a/configure b/configure
index 2065fcdf6f4ce3af7b5570b3092804027af68df9..71eef6c10858d233ec30312ed9252ed54cde7c1e 100755 (executable)
--- a/configure
+++ b/configure
@@ -51,6 +51,7 @@ CXXFLAGS_for_sh=${CXXFLAGS:-${CFLAGS}}
 CXXFLAGS=${CXXFLAGS:-\$(CFLAGS)}
 LDFLAGS=${LDFLAGS:-}
 XAPIAN_CONFIG=${XAPIAN_CONFIG:-xapian-config}
+PYTHON=${PYTHON:-}
 
 # We don't allow the EMACS or GZIP Makefile variables inherit values
 # from the environment as we do with CC and CXX above. The reason is
@@ -407,7 +408,7 @@ fi
 printf "Checking for python... "
 have_python=0
 
-for name in python python2 python3; do
+for name in ${PYTHON} python python2 python3; do
     if command -v $name > /dev/null; then
        have_python=1
        python=$name