Allow long unbreakable strings

We already allow HTTP URLs to ignore the linebreak limit. There are
other reasons to need tokens longer than 80 characters, such as internal
reference names. Allow any length of token so long as it is the only
token on the line.

Change-Id: Iee3e90a5d22d1c4b1180a3f3028b2d4c29cd3377

tests/test_titles.py

@@ -72,6 +72,9 @@ class TestTitles(testtools.TestCase):
         for i, line in enumerate(raw.split("\n")):
             if "http://" in line or "https://" in line:
                 continue
+            # Allow lines which do not contain any whitespace
+            if re.match("\s*[^\s]+$", line):
+                continue
             self.assertTrue(
                 len(line) < 80,
                 msg="%s:%d: Line limited to a maximum of 79 characters." %