Make TestCodeHilite work with Pygments ≥ 2.1.1

New versions of Pygments insert <span></span> blocks in the beginning
of the generated output sometimes [1], so we need to remove those blocks
before doing the actual checking.

[1]: https://bitbucket.org/birkenfeld/pygments-main/commits/164574c13533

Author: mitya57

tests/test_extensions.py

@@ -209,7 +209,7 @@ def testHighlightLinesWithColon(self):
             if self.has_pygments:
                 self.assertStartsWith(
                     '<div class="codehilite"><pre><span class="hll"',
-                    md.convert(text)
+                    md.convert(text).replace('<span></span>', '')
                 )
             else:
                 self.assertEqual(
@@ -330,7 +330,7 @@ def testFencedCodeWithHighlightLines(self):
         if self.has_pygments:
             self.assertStartsWith(
                 '<div class="codehilite"><pre><span class="hll"',
-                md.convert(text)
+                md.convert(text).replace('<span></span>', '')
             )
         else:
             self.assertEqual(
@@ -365,7 +365,7 @@ def testFencedLanguageAndHighlightLines(self):
             if self.has_pygments:
                 self.assertStartsWith(
                     '<div class="codehilite"><pre><span class="hll"',
-                    md.convert(text)
+                    md.convert(text).replace('<span></span>', '')
                 )
             else:
                 self.assertEqual(