variable_set concurreny fix

[elmuerte]

I just submitted a fix for the variable_set concurreny problem, it's a backport from the drupal 4.7 implementation.

variable_set first deletes the old value before inserting the new one, this ofcourse creates a concurrency issue.

this fix should prevent the database errors often created by the cron script and poormanscron module

[elmuerte]

Oh, and I also applied the url alias patch (the backport from 4.7).
As this research shows (http://www.vbdrupal.org/forum/showpost.php?p=568&postcount=7) the impact for small sites (<500 url aliases) is minimal and the gain for larger sites is exponential.

[tamarian]

Cool, will include in next release. Unless you'd like to make the next release yourself? You do have the file system access/release keys :)