get_dev_uuid_var_path: Fix theoretical shell quoting problem.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

scripts/lib/zulip_tools.py

@@ -157,8 +157,8 @@ def get_dev_uuid_var_path(create_if_missing=False):
             zulip_uuid = str(uuid.uuid4())
             # We need root access here, since the path will be under /srv/ in the
             # development environment.
-            run_as_root(["/bin/bash", "-c",
-                         "echo %s > %s" % (zulip_uuid, uuid_path)])
+            run_as_root(["sh", "-c", 'echo "$1" > "$2"', "-",
+                         zulip_uuid, uuid_path])
         else:
             raise AssertionError("Missing UUID file; please run tools/provision!")