RST reader: fix logic for ending comments.

Previously comments sometimes got extended too far.  Closes #7134.

src/Text/Pandoc/Readers/RST.hs

@@ -613,8 +613,9 @@ comment = try $ do
   string ".."
   skipMany1 spaceChar <|> (() <$ lookAhead newline)
   -- notFollowedBy' directiveLabel -- comment comes after directive so unnec.
-  manyTill anyChar blanklines
+  _ <- anyLine
   optional indentedBlock
+  optional blanklines
   return mempty
 
 directiveLabel :: Monad m => RSTParser m Text

test/command/7134.md

@@ -0,0 +1,16 @@
+```
+% pandoc -f rst -t native
+This is a paragraph.
+
+    This is a block quote.
+
+..
+
+    This should be a second block quote.
+^D
+[Para [Str "This",Space,Str "is",Space,Str "a",Space,Str "paragraph."]
+,BlockQuote
+ [Para [Str "This",Space,Str "is",Space,Str "a",Space,Str "block",Space,Str "quote."]]
+,BlockQuote
+ [Para [Str "This",Space,Str "should",Space,Str "be",Space,Str "a",Space,Str "second",Space,Str "block",Space,Str "quote."]]]
+```