Thanks @cwickens for the confirmation. It's still weird that I used one of the problematic strings in the repo and it didn't crash with 3.7.0 on my Ubuntu machine. I tried testing with Mac OS again since you mentioned it was reproducible now. I cloned the repo and even with the normal repo it crashes with 3.7.0 on Mac. I installed 3.7.1 RC1 and it fixes the issue. 

Please find my testing as below with the default clone from git : 

Python 3.7.0 for Mac OS installed from python.org segfaults : 

➜  py37bug git:(master) python3.7 -m ../venv py37-venv
➜  py37bug git:(master) source ../venv py37-venv/bin/activate
(py37-venv) ➜  py37bug git:(master) python3.7
Python 3.7.0 (v3.7.0:1bf9cc5093, Jun 26 2018, 23:26:24)
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> ^D
(py37-venv) ➜  py37bug git:(master) pip install otree
(py37-venv) ➜  py37bug git:(master) otree resetdb --noinput
[1]    2590 segmentation fault  otree resetdb --noinput


Python 3.7.1 RC 1 for Mac OS installed from python.org works fine : 

➜  py37bug git:(master) python3.7 -m ../venv py37-rc-1-venv
➜  py37bug git:(master) source ../venv py37-rc-1-venv/bin/activate
(py37-rc-1-venv) ➜  py37bug git:(master) python3.7
Python 3.7.1rc1 (v3.7.1rc1:2064bcf6ce, Sep 26 2018, 03:09:51)
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> ^D
(py37-rc-1-venv) ➜  py37bug git:(master) pip install otree
(py37-rc-1-venv) ➜  py37bug git:(master) otree resetdb --noinput
INFO Database engine: SQLite
INFO Retrieving Existing Tables...
INFO Dropping Tables...
INFO Creating Database 'default'...
Operations to perform:
  Synchronize unmigrated apps: auth, channels, contenttypes, demoapp, djhuey, forms, idmap, messages, otree, sessions, staticfiles
  Apply all migrations: (none)
Synchronizing apps without migrations:
  Creating tables...
    Creating table otree_pagecompletion
    Creating table otree_pagetimeout
    Creating table otree_completedgroupwaitpage
    Creating table otree_completedsubsessionwaitpage
    Creating table otree_participanttoplayerlookup
    Creating table otree_participantlockmodel
    Creating table otree_undefinedformmodel
    Creating table otree_roomtosession
    Creating table otree_failedsessioncreation
    Creating table otree_participantroomvisit
    Creating table otree_browserbotslaunchersessioncode
    Creating table otree_chatmessage
    Creating table otree_session
    Creating table otree_participant
    Creating table auth_permission
    Creating table auth_group
    Creating table auth_user
    Creating table django_content_type
    Creating table django_session
    Creating table demoapp_subsession
    Creating table demoapp_group
    Creating table demoapp_player
    Running deferred SQL...
Running migrations:
  No migrations to apply.
INFO Created new tables and columns.

For some odd reason even with Python 3.7.0 installed the segfault still shows 3.7.1RC1 in my Mac OS report. I had RC1 installed first and then did an install of 3.7.0 for testing this so I don't know why it's not updated to 3.7.0 in the segfault but my tests show with 3.7.1RC1 it works fine. If you can try with 3.7.1 RC1 as you are available then it will be a helpful confirmation. Attaching the core dump similar to yours for reference.

Hope it helps. 

Thanks