Add default value for CI env

issue10455
review332961002

tox.ini

@@ -3,4 +3,4 @@ envlist = py36,py37,py38,py39
 
 [testenv]
 commands = {envpython} setup.py test
-install_command = pip install --pre --find-links https://trydevpi.tryton.org/?local_version={env:CI_JOB_ID:{env:CI_BUILD_NUMBER}.{env:CI_JOB_NUMBER}} {opts} {packages}
+install_command = pip install --pre --find-links https://trydevpi.tryton.org/?local_version={env:CI_JOB_ID:{env:CI_BUILD_NUMBER:}.{env:CI_JOB_NUMBER:}} {opts} {packages}