logging: try to avoid using ANSI color codes when not logging to a terminal Color on the console is nice, but it is annoying to get these codes when for example redirecting to a file. The formatter doesn't know exactly where the message will be used - it is fully configurable. In the default configuration, the messages are passed to a StreamHandler to sys.stderr . As an approximate optmization, hardcode the color formatters to only emit color formatting if logging to something that isatty.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.