Normalize adding (and allowing missing) trailing newlines for READMEs.

Author: DavidSouther

.tools/readmes/render.py

@@ -304,6 +304,7 @@ def render(self) -> RenderStatus:
             customs=customs,
             unsupported=unsupported,
         )
+        self.readme_text += "\n" # Jinja is the worst and strips trailing new lines
         [text, errors] = expand_all_entities(self.readme_text, self.scanner.doc_gen.entities)
         if errors:
             raise errors

.tools/readmes/runner.py

@@ -173,6 +173,12 @@ def main():
 
 def make_diff(renderer, id):
     current = renderer.read_current().split("\n")
+    if current[-1] != "":
+        # Ensure final "last" line
+        current += [""]
     expected = renderer.readme_text.split("\n")
+    if expected[-1] != "":
+        # Ensure final "last" line
+        expected += [""]
     diff = unified_diff(current, expected, f"{id}/current", f"{id}/expected")
     return "\n".join(diff)