This PR was merged into the 1.2-dev branch.

Discussion
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only write lock when its content has changed

Fixed #379 by only writing the Lockfile when something has changed (which is not the case on `composer install`).

This seems to me the best solution for the linked issue:
* no change in the Flex behaviour on `composer install` needed (still doing the same like on `composer update`)
* only update the Lockfile when needed (even the modification timestamp will stay the same)
* working for all composer actions (because of auto detection)

Thank you for your feedback.

Commits
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ffe345f only write lock when its content has changed

This PR was squashed before being merged into the 1.5-dev branch.

Discussion
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compare data before marking lock as changed

In #479 I tried to fix the issue #379 by introducing a _changed_ flag to the Lock.

This patch worked for a few months. However, introducing #576 broke the patch by [always calling](https://github.com/symfony/flex/pull/576/files#diff-46b78198ae7ea525f04268205dd782c3R273) `set` ending in the same situation as before.

Blame on me for not checking if anything differs before setting the _changed_ flag. This PR tries to do better.

Commits
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bc400be compare data before marking lock as changed