Heat a large pot over medium-high heat. Add the bacon and cook until browned, about 5 minutes. Remove with a slotted spoon and transfer to a paper-towel-lined plate.
Season the chicken with salt and pepper and dredge in flour, shaking off the excess. Add the olive oil to the drippings in the pot. Add the chicken in batches and cook over medium-high heat until golden on the bottom, 6 to 7 minutes, then flip and sear the other side, about 1 minute.
Add the beer, onions, potatoes, mustard, sugar, thyme and 1 cup water to the pot and stir, making sure the chicken is fully submerged. Simmer until the chicken is cooked through, about 20 minutes. Stir in the bacon and parsley.