"DepCompareOp" stands for "dependency comparison operator", i.e. "=", "<=", ">=", "<<" or ">>", used to compare package versions. The message comes from
apt, and is printed when a package is encountered with a "Provides" declaration including a non-equal dependency comparison operator, which is invalid. (
dpkg now supports versioned-provides, which is why the error message changed to explicitly mention non-equal operators.)
So basically, a package can declare
control file and be fine, or (since mid-2014)
Provides: some-other-package (= version)
Provides: some-other-package (<< version)
In the past, any mention of a version would have caused
apt-based tools to print
Ignoring Provides line with DepCompareOp for package ...
whereas nowadays only the latter will produce
Ignoring Provides line with non-equal DepCompareOp for package ...