Fix Python linting/testing issues

(cherry picked from commit aa3e7fb)

Author: DougGregor

utils/build_swift/build_swift/driver_arguments.py

@@ -592,7 +592,8 @@ def create_argument_parser():
     option(['--back-deploy-concurrency'], toggle_true('build_backdeployconcurrency'),
            help='build back-deployment support for concurrency')
 
-    option(['--install-back-deploy-concurrency'], toggle_true('install_backdeployconcurrency'),
+    option(['--install-back-deploy-concurrency'],
+           toggle_true('install_backdeployconcurrency'),
            help='install back-deployment support libraries for concurrency')
 
     option(['--libcxx'], toggle_true('build_libcxx'),

utils/build_swift/tests/expected_options.py

@@ -166,6 +166,7 @@
     'only_executable_test': False,
     'only_non_executable_test': False,
     'infer_dependencies': False,
+    'install_backdeployconcurrency': False,
     'install_prefix': targets.install_prefix(),
     'install_symroot': None,
     'install_destdir': None,
@@ -468,7 +469,8 @@ class BuildScriptImplOption(_BaseOption):
     SetOption('--skip-watchos', dest='watchos', value=False),
 
     SetTrueOption('--back-deploy-concurrency', dest='build_backdeployconcurrency'),
-    SetTrueOption('--install-back-deploy-concurrency', dest='install_backdeployconcurrency'),
+    SetTrueOption('--install-back-deploy-concurrency',
+                  dest='install_backdeployconcurrency'),
     SetTrueOption('--benchmark'),
     SetTrueOption('--clean'),
     SetTrueOption('--dry-run'),