A typically vague BBC report informs us that "Libyan forces" have retaken control of the port in the city of Sirte, after fierce fighting with militants from so-called Islamic State. We are only told several lines in that these "forces" are "aligned to" the "UN-backed unity government" in Tripoli. This vagueness is aimed at obscuring (first) that Libya has no functional government—or three rival governments, of which the "UN-backed" one is the weakest by far. It is also aimed at obscuring that the "UN-backed" government has no armed forces—just autonomous militias that recognize its authority in a token way. For a clearer picture, we have to turn to the Libyan press. A report in the Libyan Herald tells us that the militia force battling ISIS at Sirte is from the city of Misrata, and also notes that it has carried out air-strikes in the battle for the city—indicating that these autonomous militias now have warplane. Libyan Observer identifies one of the Misrata militias as al-Bunyan al-Marsoos—and notes that it is resisting an ISIS effort retake to retake the port. 

So contrary to what you might glean from a cursory review of the headlines, the Libyan government has not retaken Sirte. Militias aligned with one of the three rival Libyan governments have retaken the port facility in the city, and the battle is not over.