Continuous Deployment - Changes in Sitecore 9

While working on some changes to our current continuous deployment process I came across an interesting change in Sitecore's .update package installer. Update packages cannot overwrite any config files that contain connectionstring in their path.

This likely won't affect many CD deployment implementations but if it does you aren't crazy. It really IS preventing updates to some configs :)

Example code from Sitecore.Update.dll checking to see if a path is 'safe':

...
if (!this.IsSafeConfigFile(mappedPath))
  {
    collistionBehavior = CollisionBehavior.Skip;
...

and here we see that paths containing connectionstring are not safe:

protected virtual bool IsSafeConfigFile(string mappedPath)
{
  return !mappedPath.ToLowerInvariant().Contains("connectionstring");
}