You can look at the recent build history at https://travis-ci.com/travis-ci/cpython-builder/builds. If you are interested in finding your Python version build log, you can use the CLI:
$ travis history --limit 100 --com -r travis-ci/cpython-builder | grep VERSION=3\.5-dev #8019 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200211T103640Z #8012 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200210T103548Z #8005 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200209T103354Z #7998 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200208T103311Z #7985 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200206T103831Z #7978 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200205T103443Z #7971 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200204T103350Z #7964 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200203T103121Z #7957 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200202T102952Z #7950 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200201T103009Z #7943 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200131T102807Z #7936 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200130T152259Z #7929 passed: default build branch=default; source=rake; env="VERSION=3.5-dev" 20200129T102653Z $ travis open --com -r travis-ci/cpython-builder 8012
The build process does go through changes, of course, but for the most part they are pretty stable. If the *-dev version behaviors change, the changes are most likely due to the changes upstream.