Issue #3422

https://github.com/composer/composer/issues/3422
Don't display the dev warning time when running self-update

Use the Application::find() method to resolve the command name, as Application::getCommandName() only returns whatever was entered as the first argument.
If the user only entered enough of the command to be unambiguous (eg self-up) then the warning would still show
By calling Application::find() we ensure that if we are going to run the self-update command then we will not show the warning, no matter what the user entered
Added some tests for the dev version warning
Backup/restore Composer environment variables

The tests could fail if an environment variable replaces an expected
value.
Revert "Backup/restore Composer environment variables"

This reverts commit 725a4fd638c7f339cdf5f1daaff0899bdbca24d3.
Allow reading of COMPOSER_ environment variables to be disabled
Update config tests to not use environment variables
Remove unused selectNewestPackages method in DefaultPolicy

Unused as of 1b6f57e6515f6a81edd11572686eb389183f2636
Merge pull request #3448 from cs278/config-env-test

Fix config tests when environment variables are set
Merge pull request #3264 from duncan3dc/remove-self-update-warning

Don't display the dev warning time when running self-update
Merge pull request #3423 from Michael-Gusev/patch-1

Issue #3422
add COMPOSER_PREFER_LOWEST_STABLE