Remove unneeded content from within `with` statements

sphinx/builders/changes.py

@@ -137,15 +137,16 @@ class ChangesBuilder(Builder):
                         __('could not read %r for changelog creation'), docname
                     )
                     continue
-            targetfn = os.path.join(self.outdir, 'rst', os_path(docname)) + '.html'
-            ensuredir(os.path.dirname(targetfn))
-            with open(targetfn, 'w', encoding='utf-8') as f:
             text = ''.join(hl(i + 1, line) for (i, line) in enumerate(lines))
             ctx = {
                 'filename': str(self.env.doc2path(docname, False)),
                 'text': text,
             }
-                f.write(self.templates.render('changes/rstsource.html', ctx))
+            rendered = self.templates.render('changes/rstsource.html', ctx)
+            targetfn = os.path.join(self.outdir, 'rst', os_path(docname)) + '.html'
+            ensuredir(os.path.dirname(targetfn))
+            with open(targetfn, 'w', encoding='utf-8') as f:
+                f.write(rendered)
         themectx = {
             'theme_' + key: val for (key, val) in self.theme.get_options({}).items()
         }

sphinx/ext/imgmath.py

@@ -304,7 +304,8 @@ def render_math(
 
 def render_maths_to_base64(image_format: str, generated_path: str) -> str:
     with open(generated_path, 'rb') as f:
-        encoded = base64.b64encode(f.read()).decode(encoding='utf-8')
+        content = f.read()
+    encoded = base64.b64encode(content).decode(encoding='utf-8')
     if image_format == 'png':
         return f'data:image/png;base64,{encoded}'
     if image_format == 'svg':

sphinx/util/docutils.py

@@ -403,8 +403,9 @@ class SphinxFileOutput(FileOutput):
             and os.path.exists(self.destination_path)
         ):
             with open(self.destination_path, encoding=self.encoding) as f:
+                on_disk = f.read()
             # skip writing: content not changed
-                if f.read() == data:
+            if on_disk == data:
                 return data
 
         return super().write(data)

utils/babel_runner.py

@@ -84,7 +84,8 @@ def run_extract() -> None:
     log = _get_logger()
 
     with open('sphinx/__init__.py', encoding='utf-8') as f:
-        for line in f.read().splitlines():
+        lines = f.readlines()
+    for line in lines:
         if line.startswith('__version__ = '):
             # remove prefix; strip whitespace; remove quotation marks
             sphinx_version = line[14:].strip()[1:-1]