Added a markdown abbrevation test case.

test/command/md-abbrevs.md

@@ -0,0 +1,31 @@
+Pandoc recognizes an abbreviation and inserts a nonbreaking
+space (among other things, this prevents a sentence-ending
+space from being inserted in LaTeX output).
+
+```
+% pandoc -t native
+Mr. Bob
+^D
+[Para [Str "Mr.\160Bob"]]
+```
+
+Here pandoc readjusts the softbreak so that the nonbreaking
+space can be inserted:
+
+```
+% pandoc -t native
+Hi Mr.
+Bob
+^D
+[Para [Str "Hi",SoftBreak,Str "Mr.\160Bob"]]
+```
+
+If you don't want this to happen you can escape the period:
+
+```
+% pandoc -t native
+Hi Mr\. Bob
+^D
+[Para [Str "Hi",Space,Str "Mr.",Space,Str "Bob"]]
+```
+