[FS#1155] sysupgrade always backups changed files in /etc, regardless of option flag

[LEDE Bugs]

The following task has a new comment added:

FS#1155 - sysupgrade always backups changed files in /etc, regardless of option flag
User who did this - Jo-Philipp Wich (jow-)

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The "-c" option was never meant to be an opt-in for the keep mechanism. It merely provides an altenrative strategy for discovering and keeping files during upgrades.

To perform a system upgrade without backups, use the "-n" flag.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1155#comment3799