3.9.0 pip-compile drops an extra from the results

[nedbat]

With 3.8.0, pip-compile put "edx-opaque-keys[django]==1.0.1" into the results, but 3.9.0 only puts "edx-opaque-keys==1.0.1". See #851 for the full reproduction.

[atugushev]

@nedbat thanks for the issue and good catch!

I've found that this problem is not related to the certain release. You can try run several times pip-compile on 3.8.0 and get edx-opaque-keys[django]==1.0.1 or edx-opaque-keys==1.0.1. See:

$ cat requirements.in
-e git+https://github.com/edx/django-rest-framework-oauth.git@0a43e8525f1e3048efe4bc70c03de308a277197c#egg=djangorestframework-oauth==1.1.1
edx-enterprise==1.7.2

$ pip-compile --version
pip-compile, version 3.8.0

$ seq 1 10| while read i; do echo "---- $i ----" && pip-compile -rqo- | grep ^edx-opaque-keys; done
---- 1 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise
---- 2 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise
---- 3 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise
---- 4 ----
edx-opaque-keys==1.0.1    # via edx-drf-extensions, edx-enterprise
---- 5 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise
---- 6 ----
edx-opaque-keys==1.0.1    # via edx-drf-extensions, edx-enterprise
---- 7 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise
---- 8 ----
edx-opaque-keys==1.0.1    # via edx-drf-extensions, edx-enterprise
---- 9 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise
---- 10 ----
edx-opaque-keys[django]==1.0.1  # via edx-drf-extensions, edx-enterprise```

[atugushev]

Possible related to #603.

[atugushev]

FTR, I can't reproduce it anymore.

[atugushev]

Reproduced in #1153.