Fix the spawn test in the bypy environment

Required the launcher to be built since the pre-built
one was being used. Fixes #2881

bypy/init_env.py

@@ -47,6 +47,18 @@ def build_c_extensions(ext_dir, args):
     shutil.copytree(
         KITTY_DIR, writeable_src_dir, symlinks=True,
         ignore=shutil.ignore_patterns('b', 'build', 'dist', '*_commands.json', '*.o'))
+
+    # Build the launcher as it is needed for the spawn test
+    try:
+        os.remove(os.path.join(writeable_src_dir, 'kitty', 'launcher', 'kitty'))
+    except FileNotFoundError:
+        pass
+    if run(PYTHON, 'setup.py', 'build-launcher', cwd=writeable_src_dir) != 0:
+        print('Building of kitty launcher failed', file=sys.stderr)
+        os.chdir(KITTY_DIR)
+        run_shell()
+        raise SystemExit('Building of kitty launcher failed')
+
     cmd = [PYTHON, 'setup.py']
     bundle = 'macos-freeze' if ismacos else 'linux-freeze'
     cmd.append(bundle)