If abc is invoked with no flags/arguments, then the setup slack decreases

[leeway64]

I encountered an abc issue where, in a Yosys script, if I call abc with no additional flags or arguments, then the setup slack decreases (as shown in the openroad report_checks command).

I wasn't sure whether to file the issue under ABC or Yosys, so I decided to file it under ABC. Please let me know if the issue should be filed under Yosys.

If anyone has the chance, could they take a look at the issue I filed here please? berkeley-abc/abc#446

Thank you!