Issue 11362 - Unit test assertion failure messages not printed

Issue URL: http://d.puremagic.com/issues/show_bug.cgi?id=11362
Regression commit from pull #636: db7dc40ad4a8e9ea9827224d8d4d799ef24810ca

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And example of how people like to kill "needless" safe utils and start use of C standard library. Here we are happy it's just a coder mistake that almost nobody of experienced developers discovered but there are also C library bugs in our world.

IMO, we should kill the usage of C library instead and provide small fast wrappers of OS API like the late `rt.util.console` did.