Following the train of events
Its quite fun to try and reconstruct what happened here.
The apparently non-culpable author, Fahad Kureshi, did a thesis on FFT optimisation in the Swedish group supervised by the same prof (Gustavsson). In his thesis he lists 10+ publications with Gustavsson on FFT optimisation, including hardware-level tweaks. Therefore he is no amateur and has the full confidence and respect of the Swedish group.
In the thanks list, he acknowledges "My friends and colleagues in Pakistan for their help and care..." and then goes further to mention: My friends... ___Imran Qureshi___ ..... for their kind help in proof reading my thesis.
So the first author of the plagiarising paper (unless its another Imran Qureshi, there are a lot of Kureshis/Qureshis about)..... proofread the thesis of a guy from the group delivering the original work. He didn't do a good job, its still has quite a few spelling and grammar mistakes.
Lets make assumptions:
(1) Imran (Q/K)ureshi asks Fahad Kureshi is he can lift an unpublished chunk of the thesis that he's written, saying yes I'll credit you for the work you've done.
(2) Imran's paper still doesn't have enough meat so he just follows the threads that he already has from Fahad's work and ends up with a duplicate of what Ingmarrson ended up doing under Gustavsson's supervision.
(3) Imran goes to his supervisor, Dr Gulam Shaikh, who is busy with teaching, underpaid and very stressed from the difficulties of life in Karachi. Ingmarrson's paper isn't out, so they publish, claiming to have a legit collaboration with Gustavsson's group, although not actually Gustavsson, which is unthinkable to the hierarchically-minded aryans over in Linkoping.
(4) Gustavsson points out that priority comes from first submission to a journal, not first publication. Despite (maybe) only having been somewhat cheeky, the Pakistani group are obliged to back down. Their mistakes were (1) Treading on Gustavsson's toes by working in a field he was busy in. (2) Using information from his (former?) grad student to steal a lead.
Fahad Kureshi will get a telling off for leaking, but most likely be forgiven.
Imran Kureshi and his boss are going to come in for a lot of hate, I would be interested if either of them reads this post if they could tell me how well I reconstructed this...