Fix up tests and eliminate a warning.

wwt_data_formats/cli.py

@@ -657,6 +657,8 @@ def wtml_report(settings):
         mywarn("ImageSet has no credits")
         credits_plain_report = credits_tag_report = ["(none)"]
     else:
+        # NB this can cause MarkupResemblesLocatorWarning if the text is short
+        # and contains no HTML tags
         credits_plain_report, credits_tag_report = process_html(imgset.credits)
 
     if not imgset.credits_url:

wwt_data_formats/tests/test1_rel.wtml

@@ -17,7 +17,7 @@
                 OffsetY="1.3867980621800038e-05" Permission="0" Projection="Tan"
                 Rotation="50.320000000000306" Sparse="True" StockSet="False" TileLevels="7"
                 Url="L{1}X{2}Y{3}.png" WidthFactor="2">
-        <Credits>NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA)</Credits>
+        <Credits>NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI,AURA)</Credits>
         <CreditsUrl>https://www.spacetelescope.org/images/heic0707a/</CreditsUrl>
         <Description>Hubble's view of the Carina Nebula ...</Description>
         <ThumbnailUrl>thumb.jpg</ThumbnailUrl>

wwt_data_formats/tests/test_server.py

@@ -24,6 +24,7 @@ class TestRunServer(object):
         settings = Namespace()
         settings.port = cls.server_port
         settings.root_dir = test_path()
+        settings.heartbeat = False
 
         # Note: there can be a race condition between server startup and the
         # execution of the tests. There doesn't seem to be any mechanism to