Gerund or Present Participle?

Solution 1:

It is a participle predicatively adjected to programmers. If it were a gerund, it would have to be capable of being interpreted as a noun substantive, which it is not.

It may help to expand the sentence into

Which is exactly what you don't want your programmers to be learning.

What you don't want is a situation where

Your programmers are learning ...

Here, learning is clearly a predicative adjective. The fact that what is the object of learning qua verb does not prevent the latter from also having the function of an adjective.

Note that, as far as the distinction between participle and gerund is concerned, one needs only consider that participles are adjectives while gerunds are substantives. If the progressive aspect associated with present participles is here absent, this does not mean that learning is not a present participle, but rather that the progressive aspect does not always follow present participles.