brix11: incorrect variable splitting

[papperlapapp]

Product AXCIOMA

Version Current HEAD (0f6dccac)

Describe the bug Variable values containing an equal sign can't be used with the "-D" option.

To Reproduce

$ bin/brix11 -D A=B=C environment
export A=B

Expected behavior

$ bin/brix11 -D A=B=C environment
export A=B=C

Output None

Environment: Output of ruby -v: ruby 3.0.4p208 (2022-04-12 revision 3fa771dded) [x86_64-linux]

Additional context None