== crash between steps, then resume
$ CRASH_AT='after summarize' python workflow.py --thread r1 --version 2.5.0
finished collect
finished summarize
!! process killed in after summarize
(exit 1)
$ python workflow.py --thread r1
resuming r1 at write_file
finished write_file
finished announce
(exit 0)
== crash inside a step with a side effect
$ CRASH_AT='announce' python workflow.py --thread r2 --version 2.5.1
finished collect
finished summarize
finished write_file
!! process killed in announce
(exit 1)
$ python workflow.py --thread r2
resuming r2 at announce
finished announce
(exit 0)
== resume under a new thread id
$ CRASH_AT='after summarize' python workflow.py --thread r3 --version 2.5.2
finished collect
finished summarize
!! process killed in after summarize
(exit 1)
$ python workflow.py --thread r3-retry --version 2.5.2
finished collect
finished summarize
finished write_file
finished announce
(exit 0)
== durability exit, then a crash
$ CRASH_AT='after summarize' python workflow.py --thread r4 --version 2.5.3 --durability exit
finished collect
finished summarize
!! process killed in after summarize
(exit 1)
$ python workflow.py --thread r4 --version 2.5.3 --durability exit
finished collect
finished summarize
finished write_file
finished announce
(exit 0)
== out/announcements.log
Released 2.5.0: out/2.5.0.md
Released 2.5.1: out/2.5.1.md
Released 2.5.1: out/2.5.1.md
Released 2.5.2: out/2.5.2.md
Released 2.5.3: out/2.5.3.md
== checkpoints saved for thread r1
  step -1 input next=['__start__'] state keys=[]
  step  0 loop  next=['collect'] state keys=['version']
  step  1 loop  next=['summarize'] state keys=['prs', 'version']
  step  2 loop  next=['write_file'] state keys=['notes', 'prs', 'version']
  step  3 loop  next=['announce'] state keys=['notes', 'path', 'prs', 'version']
  step  4 loop  next=[] state keys=['notes', 'path', 'prs', 'version']