Merge pull request #9951 from rouault/fix_test_wms_15_flake

autotest: test_wms_15: make it robust to flaky server

autotest/gdrivers/wms.py

@@ -643,11 +643,13 @@ def test_wms_14():
 def test_wms_15():
 
     srv = "http://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer?f=json&pretty=true"
-    src_ds = gdal.Open(srv)
-    if src_ds is None:
+    try:
+        src_ds = gdal.Open(srv)
+    except Exception:
         if gdaltest.gdalurlopen(srv) is None:
-            pytest.skip()
+            pytest.skip(f"{srv} not available")
         pytest.fail()
+
     ds = gdal.GetDriverByName("WMS").CreateCopy("/vsimem/wms.xml", src_ds)
     src_ds = None
     assert ds, "failed to copy"