[BUGS] Git v2.51.2 on NonStop

I have found new defects on 2.51.2 that were not present in 2.51.1 when building with OpenSSL 3.5 (probably unrelated).

Many failures in t7900 resulting from the use of test_subcommand ! as seen below. This is run in bash 5.0.18:

+ test_subcommand git gc --quiet --no-detach --skip-foreground-tasks
+ 0< run-no-auto.txt
{"event":"child_start","sid":"20251028T172435.690328Z-H36b1c598-P7b00002d","thread":"main","time":"2025-10-28T17:24:35.879833Z","file":"/home/jenkinsbuild/.jenkins/workspace/Git_Pipeline/run-command.c","line":740,"child_id":2,"child_class":"?","use_shell":false,"argv":["git","gc","--quiet","--no-detach","--skip-foreground-tasks"]}
+ test_subcommand ! git gc --auto --quiet --no-detach --skip-foreground-tasks
+ 0< run-auto.txt
test_subcommand[5]: test: argument expected

Regards, Randall