Issue #15819: tweak logic in previous commit (e0a2b14a3cf9).
diff --git a/configure b/configure
index f2304f6..6b4235c 100755
--- a/configure
+++ b/configure
@@ -5180,7 +5180,7 @@
BUILDDIR="`pwd`"
-if test "$srcdir" != "$BUILDDIR"; then
+if test "$srcdir" != "." -a "$srcdir" != "$BUILDDIR"; then
# If we're building out-of-tree make sure Include (in the current dir)
# gets picked up before its $srcdir counterpart in order for Python-ast.h
# and graminit.h to get picked up from the correct directory.