rez-suite broken in 2.104.7- cannot add second context

The following fails for me:
## generate two contexts from two different packages
rez env sgq_schema -o sgqschema.rxt
rez env am_query -o amquery.rxt

## create the suite
rez suite --create ./misc_suite

## add the first context
rez suite --add ./sgqschema.rxt --context sqgschema

# attempt to add the second context per the documentation
rez suite --add ./amquery.rxt --context amquery

```
Traceback (most recent call last):
File "/laika/depts/prod_tech/rez/lib/python/linux/rez/bin/rez/rez-suite", line 8, in
sys.exit(run_rez_suite())
File "/net/ent-prod.nfs.laika.com/ifs/laika/depts/prod_tech/rez/lib/python/linux/rez-2.104.7/lib/python2.7/site-packages/rez/cli/_entry_points.py", line 239, in run_rez_suite
return run("suite")
File "/net/ent-prod.nfs.laika.com/ifs/laika/depts/prod_tech/rez/lib/python/linux/rez-2.104.7/lib/python2.7/site-packages/rez/cli/_main.py", line 191, in run
returncode = run_cmd()
File "/net/ent-prod.nfs.laika.com/ifs/laika/depts/prod_tech/rez/lib/python/linux/rez-2.104.7/lib/python2.7/site-packages/rez/cli/_main.py", line 183, in run_cmd
return func(opts, opts.parser, extra_arg_groups)
File "/net/ent-prod.nfs.laika.com/ifs/laika/depts/prod_tech/rez/lib/python/linux/rez-2.104.7/lib/python2.7/site-packages/rez/cli/suite.py", line 200, in command
suite.save(opts.DIR)
File "/net/ent-prod.nfs.laika.com/ifs/laika/depts/prod_tech/rez/lib/python/linux/rez-2.104.7/lib/python2.7/site-packages/rez/suite.py", line 442, in save
shutil.rmtree(path)
File "/net/ent-prod.nfs.laika.com/ifs/laika/home/j/jgerber/packages/python/2.7.18/platform-linux/arch-x86_64/os-CentOS-7.7.1908/lib/python2.7/shutil.py", line 270, in rmtree
rmtree(fullname, ignore_errors, onerror)
File "/net/ent-prod.nfs.laika.com/ifs/laika/home/j/jgerber/packages/python/2.7.18/platform-linux/arch-x86_64/os-CentOS-7.7.1908/lib/python2.7/shutil.py", line 279, in rmtree
onerror(os.rmdir, path, sys.exc_info())
File "/net/ent-prod.nfs.laika.com/ifs/laika/home/j/jgerber/packages/python/2.7.18/platform-linux/arch-x86_64/os-CentOS-7.7.1908/lib/python2.7/shutil.py", line 277, in rmtree
os.rmdir(path)
OSError: [Errno 39] Directory not empty: '/net/ent-prod.nfs.laika.com/ifs/laika/dist/rel/packages/rez-suites/linux/cli_utils/contexts'
```
At the point of failure, the bin directory and suite.yaml have both been removed. (why?)

I know that this used to work with previous versions.

Reproduce the two-context sequence from the issue, then inspect rez/cli/suite.py and rez/suite.py around suite.save and the shutil.rmtree call shown in the traceback. Confirm why the second add removes bin and suite.yaml; done means both contexts are added successfully and the suite remains intact.

Written by the indexing model from the issue text.