Import upstream CPython branch '3.14'

Summary:
Python `3.14.0rc1+` (`3.14`) was **published** on 2025-07-27 06:54:41+00:00.

# Commit Info

Base: (`3.14.0rc1+`) - `5746e067fd07c9ec396e2594eb128f9418acb277` (commit date: 2025-07-25 16:08:28+00:00)

Imported: (`3.14.0rc1+`) - `3.14` (commit date: 2025-07-27 06:54:41+00:00)

Reviewed By: itamaro

Differential Revision: D79052621

fbshipit-source-id: 2b15ae27ea8342f0e1143660a84f3ffb3908dbcf

Author: generatedunixname1734921407115435

Doc/tools/templates/customsourcelink.html

@@ -4,7 +4,7 @@ <h3>{{ _('This page') }}</h3>
     <ul class="this-page-menu">
       <li><a href="{{ pathto('bugs') }}">{% trans %}Report a bug{% endtrans %}</a></li>
       <li>
-        <a href="https://github.com/python/cpython/blob/main/Doc/{{ sourcename|replace('.rst.txt', '.rst') }}"
+        <a href="https://github.com/python/cpython/blob/main/Doc/{{ sourcename|replace('.rst.txt', '.rst') }}?plain=1"
             rel="nofollow">{{ _('Show source') }}
         </a>
       </li>

Lib/test/test_perf_profiler.py

@@ -318,6 +318,7 @@ def run_perf(cwd, *args, use_jit=False, **env_vars):
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         env=env,
+        text=True,
     )
     if proc.returncode:
         print(proc.stderr, file=sys.stderr)
@@ -327,10 +328,10 @@ def run_perf(cwd, *args, use_jit=False, **env_vars):
         jit_output_file = cwd + "/jit_output.dump"
         command = ("perf", "inject", "-j", "-i", output_file, "-o", jit_output_file)
         proc = subprocess.run(
-            command, stderr=subprocess.PIPE, stdout=subprocess.PIPE, env=env
+            command, stderr=subprocess.PIPE, stdout=subprocess.PIPE, env=env, text=True
         )
         if proc.returncode:
-            print(proc.stderr)
+            print(proc.stderr, file=sys.stderr)
             raise ValueError(f"Perf failed with return code {proc.returncode}")
         # Copy the jit_output_file to the output_file
         os.rename(jit_output_file, output_file)
@@ -342,10 +343,9 @@ def run_perf(cwd, *args, use_jit=False, **env_vars):
         stderr=subprocess.PIPE,
         env=env,
         check=True,
+        text=True,
     )
-    return proc.stdout.decode("utf-8", "replace"), proc.stderr.decode(
-        "utf-8", "replace"
-    )
+    return proc.stdout, proc.stderr
 
 
 class TestPerfProfilerMixin: