Bitten by IIS, or lack thereof

Here at the office, we build a number of web applications. I recently started refactoring one such application to change and improve how we deploy it. As soon as I made the change to the .csproj to remove some old configurations and add new ones, I mysteriously started getting this error on our build machine (and only our build machine):

C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v12.0\Web\Microsoft.Web.Publishing.targets (2664): Filename: redirection.configError: Cannot read configuration file

After examining the changes I made, I figured "there's nothing that should be causing this. WTF?" Then after a while, I went on to our build machine and found that we didn't actually have IIS installed on the build machines (which is a good idea from a security standpoint, because there's really no reason for a build machine to have IIS installed). So why did this start suddenly ?

I went and examined the exact line that was causing the problem in the targets file, and the only thing that appeared to be including this conditional statement was the flag 'IncludeIisSettings'. Sure enough, the old configuration which we never used before and were using now had this set.