Rez 3.2.1 regression when building a package

[czerouni]

Describe the bug here.

Environment

• Rocky9
• 3.2.1
• 3.9.21

To Reproduce We have a package.py file that contains variants that look like this:

variants = [
    [
        "platform-linux",
        "arch-x86_64",
        "os-rocky-9",
        "gcc-9",
        "usd-21.11",
        "boost-1.73",
        "!katana",
        "!houdini",
    ]
   etc
]

In rez 3.1.1, this will build successfully. In 3.2.1, the "!katana" is interpreted as a history command in the tcsh, and the build fails with "katana: Event not found."

Expected behavior It should build the package.

Actual behavior It fails as above.

Regression 3.1.1