Auto merge of #24575 - marmeladema:issue-23607/compat, r=SimonSapin

Enable some mach commands to be run with python3

This change finally enable the following commands to be run with python3:
* `build`
* `test-unit`
* `package`

As previously explained, `test-tidy` will require more work in the wpt repository directly. Maybe `test-tidy --no-wpt` is achievable relatively quickly though.

For possible remaining bits that might need to be worked on, see https://github.com/servo/servo/issues/23607

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors

<!-- Either: -->
- [x] There are tests for these changes

<!-- Also, please make sure that "Allow edits from maintainers" checkbox is checked, so that we can help you if you get stuck somewhere along the way.-->

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

python/servo/command_base.py

@@ -27,6 +27,7 @@ import six
 import sys
 import tarfile
 import zipfile
+import functools
 from xml.etree.ElementTree import XML
 from servo.util import download_file
 import six.moves.urllib as urllib
@@ -103,15 +104,15 @@ def archive_deterministically(dir_to_archive, dest_archive, prepend_path=None):
 
         # Sort file entries with the fixed locale
         with setlocale('C'):
-            file_list.sort(cmp=locale.strcoll)
+            file_list.sort(key=functools.cmp_to_key(locale.strcoll))
 
         # Use a temporary file and atomic rename to avoid partially-formed
         # packaging (in case of exceptional situations like running out of disk space).
         # TODO do this in a temporary folder after #11983 is fixed
         temp_file = '{}.temp~'.format(dest_archive)
-        with os.fdopen(os.open(temp_file, os.O_WRONLY | os.O_CREAT, 0o644), 'w') as out_file:
+        with os.fdopen(os.open(temp_file, os.O_WRONLY | os.O_CREAT, 0o644), 'wb') as out_file:
             if dest_archive.endswith('.zip'):
-                with zipfile.ZipFile(temp_file, 'w', zipfile.ZIP_DEFLATED) as zip_file:
+                with zipfile.ZipFile(out_file, 'w', zipfile.ZIP_DEFLATED) as zip_file:
                     for entry in file_list:
                         arcname = entry
                         if prepend_path is not None:
@@ -257,7 +258,7 @@ def gstreamer_root(target, env, topdir=None):
             return env.get(gst_env)
         elif os.path.exists(path.join(gst_default_path, "bin", "ffi-7.dll")):
             return gst_default_path
-    elif sys.platform == "linux2":
+    elif is_linux():
         return path.join(topdir, "support", "linux", "gstreamer", "gst")
     return None
 
@@ -579,7 +580,7 @@ class CommandBase(object):
         if "x86_64" not in effective_target or "android" in effective_target:
             # We don't build gstreamer for non-x86_64 / android yet
             return False
-        if sys.platform == "linux2" or is_windows():
+        if is_linux() or is_windows():
             if path.isdir(gstreamer_root(effective_target, env, self.get_top_dir())):
                 return True
             else:
@@ -689,7 +690,7 @@ install them, let us know by filing a bug!")
             extra_lib = [libpath] + extra_lib
             append_to_path_env(path.join(libpath, "pkgconfig"), env, "PKG_CONFIG_PATH")
 
-        if sys.platform == "linux2":
+        if is_linux():
             distrib, version, _ = distro.linux_distribution()
             distrib = six.ensure_str(distrib)
             version = six.ensure_str(version)