diff --git a/test/test-lib.sh b/test/test-lib.sh
index 548d534..2ee6249 100644
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -18,7 +18,14 @@ if [ -z "$SHARNESS" ] || [ ! -f "$SHARNESS" ] ; then
 	exit 1
 fi
 
+# Prevent sharness from adding the source directory to PATH
+# since the scripts use unversioned python for their shebang
+# but tests should run under the python with mercurial support
+# so create an empty directory and strip it from PATH afterwards
+SHARNESS_BUILD_DIRECTORY="$(mktemp -d)"
 . "$SHARNESS"
+export PATH="${PATH#*:}"
+rmdir "$SHARNESS_BUILD_DIRECTORY"
 
 if [ -n "$PYTHON" ] && "$PYTHON" -c 'import mercurial' 2> /dev/null ; then
 	: Use chosen Python version
@@ -29,7 +36,20 @@ elif python2 -c 'import mercurial' 2> /dev/null ; then
 elif python -c 'import mercurial' 2> /dev/null ; then
 	PYTHON=python
 fi
-test -n "$PYTHON" && test_set_prereq PYTHON
+if [ -n "$PYTHON" ] ; then
+	test_set_prereq PYTHON
+
+	# Change shebang on a copy of scripts to chosen Python version
+	TEST_BIN="$SHARNESS_TRASH_DIRECTORY/bin"
+	mkdir -p "$TEST_BIN"
+	for s in git-remote-hg git-hg-helper ; do
+		printf "%s\n" "#!/usr/bin/env $PYTHON" > "$TEST_BIN/$s"
+		tail -n +2 "$SHARNESS_TEST_DIRECTORY/../$s" >> "$TEST_BIN/$s"
+		chmod u+x "$TEST_BIN/$s"
+	done
+	export PATH="$TEST_BIN${PATH:+:$PATH}"
+	unset TEST_BIN
+fi
 
 GIT_AUTHOR_EMAIL=author@example.com
 GIT_AUTHOR_NAME='A U Thor'