Strange behaviour of addprocs on Julia 1.12-rc1

General Usage
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2

Probably caused by first point in NEWS.md:

Julia now defaults to 1 “interactive” thread, in addition to the 1 default “worker” thread. i.e. -t1,1. This means in default configuration the main task and repl (when in interactive mode), which both run on thread 1, now run within the interactive threadpool. The libuv IO loop also runs on thread 1, helping efficient utilization of the worker threadpool used by Threads.@spawn. Asking for specifically 1 thread (-t1/JULIA_NUM_THREADS=1) or passing 0 will disable the interactive thread i.e. -t1,0 or JULIA_NUM_THREADS=1,0 , or -tauto,0 etc. Asking for more than 1 thread will enable the interactive thread so -t2 will set the equivalent of -t2,1 (#57087).