Custom asset handler messes unit test summary report

[ric maicle]

[dmd 2.090.1 linux 64-bit]

The following code does not report the correct unit test summary.
The report says 1 unit test passed.

~~~~~
shared static this() {
     import core.exception;
     assertHandler(&cah);
}

void
cah(string file, ulong line, string msg) nothrow {
     import core.stdc.stdio: printf;
     printf("==============================\n");
     printf("Assert error: %s %d: %s\n", file.ptr, line, msg.ptr);
     printf("==============================\n");
}

unittest {
     assert(false);
}
~~~~~