[gegl] Fix Python tests (fixes #224)

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 7a63a13e8d50c6d10adb0d47299cfc1c1d2e262b
Author: Félix Piédallu <felix piedallu me>
Date:   Tue Feb 18 12:12:37 2020 +0100

    Fix Python tests (fixes #224)

 tests/python/meson.build | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)
---
diff --git a/tests/python/meson.build b/tests/python/meson.build
index c6782e6cf..bd1451118 100644
--- a/tests/python/meson.build
+++ b/tests/python/meson.build
@@ -11,13 +11,14 @@ if python.found() and pygobject_found
   foreach testname : testnames
     testfile = 'test-' + testname + '.py'
     test(testname,
-      python,
-      args: files(testfile),
-      env: [
-        'LD_LIBRARY_PATH=' + meson.build_root() / 'gegl' + ':$LD_LIBRARY_PATH',
-        'GI_TYPELIB_PATH=' + meson.build_root() / 'gegl' + ':$GI_TYPELIB_PATH',
-        'GEGL_PATH='+ meson.build_root() / 'operations',
+      bash,
+      args: [
+        '-c',
+        'LD_LIBRARY_PATH='+ meson.build_root() / 'gegl' + ':$LD_LIBRARY_PATH',
+        'GI_TYPELIB_PATH='+ meson.build_root() / 'gegl' + ':$GI_TYPELIB_PATH',
+        'GEGL_PATH='      + meson.build_root() / 'operations',
         'GEGL_SWAP=RAM',
+        python.path(), files(testfile),
       ],
       suite: 'python',
       is_parallel: false,