python: Modernize legacy Python 2 syntax with pyupgrade.

Generated by `pyupgrade --py3-plus --keep-percent-format` on all our
Python code except `zthumbor` and `zulip-ec2-configure-interfaces`,
followed by manual indentation fixes.

Signed-off-by: Anders Kaseorg <anders@zulipchat.com>

scripts/lib/clean_emoji_cache.py

@@ -18,7 +18,7 @@ if ENV == "travis":
 
 def get_caches_in_use(threshold_days):
     # type: (int) -> Set[str]
-    setups_to_check = set([ZULIP_PATH, ])
+    setups_to_check = {ZULIP_PATH}
     caches_in_use = set()
 
     if ENV == "prod":

scripts/lib/clean_node_cache.py

@@ -25,7 +25,7 @@ if ENV == "travis":
 
 def get_caches_in_use(threshold_days):
     # type: (int) -> Set[str]
-    setups_to_check = set([ZULIP_PATH, ])
+    setups_to_check = {ZULIP_PATH}
     caches_in_use = set()
 
     if ENV == "prod":

scripts/lib/clean_venv_cache.py

@@ -20,7 +20,7 @@ if ENV == "travis":
 
 def get_caches_in_use(threshold_days):
     # type: (int) -> Set[str]
-    setups_to_check = set([ZULIP_PATH, ])
+    setups_to_check = {ZULIP_PATH}
     caches_in_use = set()
 
     def add_current_venv_cache(venv_name: str) -> None:

scripts/lib/node_cache.py

@@ -39,7 +39,7 @@ def generate_sha1sum_node_modules(setup_dir=None, production=DEFAULT_PRODUCTION)
     if os.path.exists(YARN_LOCK_FILE_PATH):
         # For backwards compatibility, we can't assume yarn.lock exists
         sha1sum.update(subprocess_text_output(['cat', YARN_LOCK_FILE_PATH]).encode('utf8'))
-    with open(YARN_PACKAGE_JSON, "r") as f:
+    with open(YARN_PACKAGE_JSON) as f:
         yarn_version = json.load(f)['version']
         sha1sum.update(yarn_version.encode("utf8"))
     sha1sum.update(subprocess_text_output(['node', '--version']).encode('utf8'))

scripts/lib/setup_venv.py

@@ -171,7 +171,7 @@ def get_venv_packages(venv_path):
     package index file.
     """
     with open(get_index_filename(venv_path)) as reader:
-        return set(p.strip() for p in reader.read().split('\n') if p.strip())
+        return {p.strip() for p in reader.read().split('\n') if p.strip()}
 
 def try_to_copy_venv(venv_path, new_packages):
     # type: (str, Set[str]) -> bool
@@ -281,7 +281,7 @@ def do_patch_activate_script(venv_path):
     # venv_path should be what we want to have in VIRTUAL_ENV after patching
     script_path = os.path.join(venv_path, "bin", "activate")
 
-    with open(script_path, 'r') as f:
+    with open(script_path) as f:
         lines = f.readlines()
     for i, line in enumerate(lines):
         if line.startswith('VIRTUAL_ENV='):

scripts/lib/upgrade-zulip-stage-2

@@ -65,7 +65,7 @@ if not args.skip_puppet:
     subprocess.check_call(["apt-get", "update"])
     subprocess.check_call(["apt-get", "-y", "upgrade"])
 
-if not os.path.exists((os.path.join(deploy_path, "zproject/prod_settings.py"))):
+if not os.path.exists(os.path.join(deploy_path, "zproject/prod_settings.py")):
     # This is normally done in unpack-zulip, but for upgrading from
     # zulip<1.4.0, we need to do it.  See discussion in commit 586b23637.
     os.symlink("/etc/zulip/settings.py",

scripts/lib/zulip_tools.py

@@ -289,7 +289,7 @@ def get_caches_to_be_purged(caches_dir, caches_in_use, threshold_days):
 
 def purge_unused_caches(caches_dir, caches_in_use, cache_type, args):
     # type: (str, Set[str], str, argparse.Namespace) -> None
-    all_caches = set([os.path.join(caches_dir, cache) for cache in os.listdir(caches_dir)])
+    all_caches = {os.path.join(caches_dir, cache) for cache in os.listdir(caches_dir)}
     caches_to_purge = get_caches_to_be_purged(caches_dir, caches_in_use, args.threshold_days)
     caches_to_keep = all_caches - caches_to_purge
 
@@ -313,7 +313,7 @@ def generate_sha1sum_emoji(zulip_path):
     # Take into account the version of `emoji-datasource-google` package
     # while generating success stamp.
     PACKAGE_FILE_PATH = os.path.join(zulip_path, 'package.json')
-    with open(PACKAGE_FILE_PATH, 'r') as fp:
+    with open(PACKAGE_FILE_PATH) as fp:
         parsed_package_file = json.load(fp)
     dependency_data = parsed_package_file['dependencies']
 
@@ -366,7 +366,7 @@ def parse_os_release():
     we avoid using it, as it is not available on RHEL-based platforms.
     """
     distro_info = {}  # type: Dict[str, str]
-    with open('/etc/os-release', 'r') as fp:
+    with open('/etc/os-release') as fp:
         for line in fp:
             line = line.strip()
             if not line or line.startswith('#'):