src/should.py: do not run at all the commands when unmet !REQUIRES or !NO_LAUNCHER

fix #65
3 jobs for 65-bug-no-launcher in 9 seconds (queued for 2 minutes and 12 seconds)
Status Job ID Name Coverage
  Unit
passed #10329
unit

00:00:03

 
  Demo
failed #10330
demo

00:00:06

 
  Coverage
skipped #10331
coverage
 
Name Stage Failure
failed
demo Demo
    s.test(open(f), variables, verbose - 1, only=only)
File "src/should.py", line 990, in test
current_test_lines += test_lines
UnboundLocalError: local variable 'test_lines' referenced before assignment
Uploading artifacts...
Runtime platform arch=386 os=linux pid=23335 revision=58272c27 version=12.7.0
should.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=10330 responseStatus=201 Created token=ST7FpF8S
ERROR: Job failed: exit status 1