OpenFileGDB: accept /vsizip/some_random_filename.zip where content is…

… directly at top-level

Example: ogrinfo /vsizip//vsicurl/https://maps.kamloops.ca/OpenData/zipfiles/ParksGDB.zip

Fixes OSGeo#11836

autotest/ogr/ogr_openfilegdb.py

@@ -2958,3 +2958,12 @@ def test_ogr_openfilegdb_weird_gdbindexes():
         lyr.SetAttributeFilter("id = '1'")
         f = lyr.GetNextFeature()
         assert f
+
+
+###############################################################################
+
+
+def test_ogr_openfilegdb_vsizip_random_zip_name_and_no_gdb_subdir():
+
+    with ogr.Open("/vsizip/data/filegdb/testopenfilegdb.zip") as ds:
+        assert ds.GetLayerCount() == 37

ogr/ogrsf_frmts/openfilegdb/ogropenfilegdbdrivercore.cpp

@@ -111,6 +111,17 @@ GDALIdentifyEnum OGROpenFileGDBDriverIdentify(GDALOpenInfo *poOpenInfo,
     }
 #endif
 
+    else if (STARTS_WITH(pszFilename, "/vsizip/") && poOpenInfo->bIsDirectory)
+    {
+        VSIStatBufL stat;
+        return VSIStatL(
+                   CPLFormFilenameSafe(pszFilename, "a00000001", "gdbtable")
+                       .c_str(),
+                   &stat) == 0
+                   ? GDAL_IDENTIFY_TRUE
+                   : GDAL_IDENTIFY_FALSE;
+    }
+
     else if (EQUAL(pszFilename, "."))
     {
         GDALIdentifyEnum eRet = GDAL_IDENTIFY_FALSE;