Fix appindicator fallback import

Before it was trying the fallback import even if the first choice
import succeeded. This resulted in confusing diagnostic messages about
failing to import the fallback on systems that only have the first
choice.

src/fluxgui/fluxapp.py

@@ -15,22 +15,18 @@
 from gi.repository import Gtk as gtk
 # As of 2022/03/23 there is no Ayatana appindicator on Fedora, so fall
 # back to using regular appindicator if necessary.
-_imported_appindicator = False
 try:
     gi.require_version('AyatanaAppIndicator3', '0.1')
     from gi.repository import AyatanaAppIndicator3 as appindicator
-    _imported_appindicator = True
 except:
     print('Failed to import Ayatana appindicator, falling back to plain appindicator ...')
-try:
-    gi.require_version('AppIndicator3', '0.1')
-    from gi.repository import AppIndicator3 as appindicator
-    _imported_appindicator = True
-except:
-    print('Failed to import plain appindicator ...')
-if not _imported_appindicator:
-    print('Failed to import an appindicator implementation, dying ...')
-    sys.exit(1)
+    try:
+        gi.require_version('AppIndicator3', '0.1')
+        from gi.repository import AppIndicator3 as appindicator
+    except:
+        print('Failed to import plain appindicator ...')
+        print('Failed to import an appindicator implementation, dying ...')
+        sys.exit(1)
 
 class FluxGUI(object):
     """