restart-server: Default to running config and database checks.

If there is a syntax error in `settings.py`, `restart-server` should
provide a reasonable message about this.  It did so prior to
af08bcdb3f, becausde any invocation `./manage.py` without
`--skip-checks` will verify `settings.py`, among several other checks.
After af08bcdb3f, there are no `./manage.py` calls in most restarts,
which fa77be6e6c took further.

Add an explicit `./manage.py check` in the default case.
upgrade-zulip-stage-2 overrides this by passing `--skip-checks`, for
performance.  This also means that `upgrade-zulip-from-git` itself
picks up the same `--skip-checks` flag, since it inherits the same
flag parsing, though that is perhaps of dubious utility.

scripts/lib/upgrade-zulip-stage-2

@@ -363,7 +363,8 @@ else:
 
 # Perform system checks -- including database checks, so we don't need
 # to do them when we do migrations, below.
-subprocess.check_call(["./manage.py", "check", "--database", "default"], preexec_fn=su_to_zulip)
+if not args.skip_checks:
+    subprocess.check_call(["./manage.py", "check", "--database", "default"], preexec_fn=su_to_zulip)
 
 # Our next optimization is to check whether any migrations are needed
 # before we start the critical section of the restart.  This saves
@@ -465,7 +466,7 @@ else:
         )
 
     logging.info("Restarting Zulip...")
-    start_args = []
+    start_args = ["--skip-checks"]
     if migrations_needed:
         start_args.append("--fill-cache")
     if IS_SERVER_UP:

scripts/lib/zulip_tools.py

@@ -645,6 +645,9 @@ def deport(netloc: str) -> str:
 def start_arg_parser(action: str, add_help: bool = False) -> argparse.ArgumentParser:
     parser = argparse.ArgumentParser(add_help=add_help)
     parser.add_argument("--fill-cache", action="store_true", help="Fill the memcached caches")
+    parser.add_argument(
+        "--skip-checks", action="store_true", help="Skip syntax and database checks"
+    )
     if action == "restart":
         parser.add_argument(
             "--less-graceful",

scripts/restart-server

@@ -41,6 +41,11 @@ if pwd.getpwuid(os.getuid()).pw_name != "zulip":
     logging.error("Must be run as user 'zulip'.")
     sys.exit(1)
 
+
+if not args.skip_checks:
+    logging.info("Running syntax and database checks")
+    subprocess.check_call(["./manage.py", "check", "--database", "default"])
+
 if args.fill_cache:
     logging.info("Filling memcached caches")
     subprocess.check_call(["./manage.py", "fill_memcached_caches", "--skip-checks"])