rest2html: treat referenced wrapped images in base document as inlined

docutils will only add newlines around images it believes are inlined.
For images held in references, it checks the parent of the reference if
its a `TextElement` to consider it inlined. Since a document is not a
`TextElement` type, it will wrap an image with newlines. For GitHub
output, this is not desired and will result in the extra whitespace
being rendered with a reference's decorative line. To avoid this,
always strip any appended suffixes for images in this scenario.

Signed-off-by: James Knight <git@jdknight.me>

Author: jdknight

lib/github/commands/rest2html

@@ -258,6 +258,12 @@ class GitHubHTMLTranslator(HTMLTranslator):
             self.body.append(self.starttag(node, 'img', **atts))
         HTMLTranslator.depart_image(self, node)
 
+        # treat images held in a reference on the base document as inlined
+        # images; this is to help avoid rendering a reference's decorative
+        # line for the spacing after an image
+        if (isinstance(node.parent, nodes.reference)
+            and isinstance(node.parent.parent, nodes.document)):
+            self.body.append(self.body.pop().rstrip('\n'))
 
 def kbd(name, rawtext, text, lineno, inliner, options={}, content=[]):
     return [nodes.raw('', '<kbd>%s</kbd>' % text, format='html')], []