Check if indented line is blank

Definition list are composed by a term and a definition block. The term
and the definition block may not be separated by a blank line. Lines
with only whitespace are considered blank.

lib/Parser/DocumentParser.php

@@ -309,7 +309,7 @@ final class DocumentParser
                         return true;
                     }
 
-                    if ($this->lineChecker->isIndented($this->lines->getNextLine())) {
+                    if (trim($this->lines->getNextLine()) !== '' && $this->lineChecker->isIndented($this->lines->getNextLine())) {
                         $this->setState(State::DEFINITION_LIST);
                         $this->buffer->push($line);
 

tests/Functional/tests/render/definition-list/definition-list.html

@@ -94,3 +94,13 @@ definition 2 </dd>
         </dd>
     </dl>
 </div>
+<div class="section" id="not-a-definition-list">
+    <h1>
+        Not a definition list
+    </h1>
+    <p>Single line followed by a blank line</p>
+    <blockquote>
+        <p>This line is indented, but because of the blank line, it should
+not be considered a term. It is a blockquote.</p>
+    </blockquote>
+</div>

tests/Functional/tests/render/definition-list/definition-list.rst

@@ -84,3 +84,11 @@ term 1
     .. note::
 
         directive in definition list
+
+Not a definition list
+=====================
+
+Single line followed by a blank line
+  
+    This line is indented, but because of the blank line, it should
+    not be considered a term. It is a blockquote.