Yet more pre-release check fixes

We need another needle for French installs, and we need to use
ISO_URL for checking the ISO file name if ISO isn't set.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

lib/utils.pm

@@ -979,6 +979,8 @@ sub check_prerelease {
     # prerelease tags should appear, otherwise they should not.
 
     my $beta = get_var('ISO');
+    # install_pxeboot tests have ISO blanked, so we must use ISO_URL
+    my $beta ||= get_var('ISO_URL');
     my $nightly = get_var('BUILD');
     my $version = get_var('VERSION');
     my $development = get_var('DEVELOPMENT');

needles/anaconda/identification/prerelease_note-french-blue-20190911.json

@@ -0,0 +1,16 @@
+{
+  "area": [
+    {
+      "xpos": 764,
+      "type": "match",
+      "height": 25,
+      "ypos": 35,
+      "width": 138
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "LANGUAGE-french",
+    "prerelease_note"
+  ]
+}