Example for this is the article for "Fallstreak hole", where the old behavior would create incorrect results when an <a> tag is nested at the beginning of a <b> tag.
Bad:
<Lily> A Nonefallstreak hole, also known as a hole punch cloud, punch hole cloud, skypunch, canal cloud or cloud hole, is a large circular or elliptical gap that can appear in cirrocumulus or altocumulus clouds. Such holes are formed when the water temperature in the clouds is below freezing but the water has not frozen yet due to the lack of ice nucleation (see supercooled water). When ice crystals do form it will set off a (1 more message)
Better:
<Lily> A fallstreak hole, also known as a hole punch cloud, punch hole cloud, skypunch, canal cloud or cloud hole, is a large circular or elliptical gap that can appear in cirrocumulus or altocumulus clouds. Such holes are formed when the water temperature in the clouds is below freezing but the water has not frozen yet due to the lack of ice nucleation (see supercooled water). When ice crystals do form it will set off a (1 more message)
