Ensure ending newline in renderer, rather than renderer and diff

.tools/readmes/render.py

@@ -333,7 +333,10 @@ def write(self):
     def read_current(self):
         try:
             with self.readme_filename.open("r", encoding="utf-8") as f:
-                return f.read()
+                current = f.read()
+                if current[-1] != "\n":
+                    # Ensure there's always an ending newline
+                    current += "\n"
         except FileNotFoundError:
             return ""
 

.tools/readmes/runner.py

@@ -173,12 +173,6 @@ 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)