Fish completion suggested completions have double parentheses

[uri-canva]

Description of the problem / feature request:

When completing an option:

> bazel info --
----auto_output_filter                                                                                                                        ((none, all, packages or subpackages; default: "none"))
----bes_backend                                                                                                                                                             ((a string; default: ""))
----bes_keywords                                                                                                                      ((comma-separated list of options; may be used multiple times))
----bes_outerr_buffer_size                                                                                                                                           ((an integer; default: "10240"))
----bes_outerr_chunk_size                                                                                                                                          ((an integer; default: "1048576"))

Note how the description of the options are wrapped in two sets of parentheses like ((none, all, packages or subpackages; default: "none")).

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Source fish completions, try to autocomplete bazel info --.

What operating system are you running Bazel on?

sw_vers
ProductName: Mac OS X
ProductVersion: 10.15.7
BuildVersion: 19H2

fish --version
fish, version 3.1.2

What's the output of bazel info release?

release 3.3.0

Have you found anything relevant by searching the web?

Issue requesting fish completions: #5088
Initial implementation: https://github.com/bazelbuild/bazel/pull/11450/files

[uri-canva]

cc @tmandry @akirabaruah