Revert unnecessary merges on 6.0.x

This commit removes unnecessary main-branch merges starting from
8750608b5b and adds the following
needed commit(s) that were made afterward:

- 5dce82c48b

git/hooks/prepare-forward-merge

@@ -4,7 +4,7 @@ require 'net/http'
 require 'yaml'
 require 'logger'
 
-$main_branch = "6.2.x"
+$main_branch = "6.0.x"
 
 $log = Logger.new(STDOUT)
 $log.level = Logger::WARN