hgext/*-format: pass PYTHONIOENCODING=UTF-8 to the mach subproces…

…s (Bug 1752583) r=mhentges

`cp1252` is the default encoding for `hg.exe`, and is making it's way
into `mach` as the preferred encoding via the inherited environment from `hg`.
This commit forces utf-8 in the call to mach, by passing `PYTHONIOENCODING`
in the environment for `mach`.

Differential Revision: https://phabricator.services.mozilla.com/D137478

--HG--
extra : moz-landing-system : lando

hgext/clang-format/__init__.py

@@ -57,7 +57,13 @@ def call_clang_format(repo, changed_files):
         clang_format_cmd = [b'python3', b'mach'] + arguments
     else:
         clang_format_cmd = [mach_path] + arguments
-    subprocess.call(clang_format_cmd)
+
+    # Set `PYTHONIOENCODING` since `hg.exe` will detect `cp1252` as the encoding
+    # and pass it as the encoding to `mach` via the environment.
+    env = dict(os.environ)
+    env["PYTHONIOENCODING"] = "utf-8"
+
+    subprocess.call(clang_format_cmd, env=env)
 
 
 def wrappedcommit(orig, repo, *args, **kwargs):

hgext/js-format/__init__.py

@@ -52,7 +52,13 @@ def call_js_format(repo, changed_files):
         js_format_cmd = [b'python3', b'mach'] + arguments
     else:
         js_format_cmd = [mach_path] + arguments
-    subprocess.call(js_format_cmd)
+
+    # Set `PYTHONIOENCODING` since `hg.exe` will detect `cp1252` as the encoding
+    # and pass it as the encoding to `mach` via the environment.
+    env = dict(os.environ)
+    env["PYTHONIOENCODING"] = "utf-8"
+
+    subprocess.call(js_format_cmd, env=env)
 
 
 def wrappedcommit(orig, repo, *args, **kwargs):