LaTeX/ImageConverter: Regression with `data:` URIs about sphinx HOT 1 OPEN

I've been investigating this, after recently modifying some image-download code -- I was wondering if that could be related. It doesn't seem to be, but I'll report some findings from along the way:

An important part of 0a76199 seems to be:

@@ -117,7 +117,7 @@ class DataURIExtractor(BaseImageConverter):
     default_priority = 150
 
     def match(self, node: nodes.image) -> bool:
-        if self.app.builder.supported_remote_images == []:
+        if not self.app.builder.supported_remote_images:
             return False
         if self.app.builder.supported_data_uri_images is True:
             return False

...in particular because LaTeXBuilder.supported_remote_images had, and still has, a boolean value (False), not a list value.

Before 0a76199, the DataURIExtractor could successfully match data URIs during latex builds: the above condition would always fail, allowing fallback to the final check for the data: protocol scheme (v7.3.0 permalink).

from sphinx.