Fixed test failure when lxml is not installed.

1 files changed, 7 insertions, 0 deletions

diff --git a/doc/source/index.rst b/doc/source/index.rst
index 734851d..5b65354 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -2670,6 +2670,13 @@ deprecated and removed in Python 3.0. Beautiful Soup 4 uses
 ``html.parser`` by default, but you can plug in lxml or html5lib and
 use that instead. See `Installing a parser`_ for a comparison.
 
+Since ``html.parser`` is not the same parser as ``SGMLParser``, it
+will treat invalid markup differently. Usually the "difference" is
+that ``html.parser`` crashes. In that case, you'll need to install
+another parser. But sometimes ``html.parser`` just creates a different
+parse tree than ``SGMLParser`` would. If this happens, you may need to
+update your BS3 scraping code to deal with the new tree.
+
 Method names
 ^^^^^^^^^^^^