rez depends -p crashes

[czerouni]

Describe the bug here.

Environment

• OS - rocky9
• Rez version - 3.0.0, 3.1.1, 3.2.1
• Rez python version - 3.9.16

To Reproduce
$ rez depends -p boost
where boost is a Rez package installed to the network

Expected behavior
Looking for rez dependencies

Actual behavior

$ rez depends --private-build-requires boost

Searching [#################               ] 188/342Traceback (most recent call last):
  File "/laika/dist/third_party/linux_rocky9_x86_64/rez/RELEASE/bin/rez/rez", line 8, in <module>
    sys.exit(run_rez())
  File "/net/ent-prod.nfs.laika.com/ifs/laika/dist/third_party/linux_rocky9_x86_64/rez/v3.1.1/lib/python3.9/site-packages/rez/cli/_entry_points.py", line 69, in run_rez
    return run()
  File "/net/ent-prod.nfs.laika.com/ifs/laika/dist/third_party/linux_rocky9_x86_64/rez/v3.1.1/lib/python3.9/site-packages/rez/cli/_main.py", line 189, in run
    returncode = run_cmd()
  File "/net/ent-prod.nfs.laika.com/ifs/laika/dist/third_party/linux_rocky9_x86_64/rez/v3.1.1/lib/python3.9/site-packages/rez/cli/_main.py", line 181, in run_cmd
    return func(opts, opts.parser, extra_arg_groups)
  File "/net/ent-prod.nfs.laika.com/ifs/laika/dist/third_party/linux_rocky9_x86_64/rez/v3.1.1/lib/python3.9/site-packages/rez/cli/depends.py", line 61, in command
    pkgs_list, g = get_reverse_dependency_tree(
  File "/net/ent-prod.nfs.laika.com/ifs/laika/dist/third_party/linux_rocky9_x86_64/rez/v3.1.1/lib/python3.9/site-packages/rez/package_search.py", line 90, in get_reverse_dependency_tree
    if not req.conflict:
AttributeError: 'str' object has no attribute 'conflict'

Regression
I tried this with 3 versions of rez, with the same result. For reference, we have compiled boost with RPATH embeds, we are not setting LD_LIBRARY_PATH in the package.py file.