bookmarks: rely on exception for malformed lines Since we already have an exception context open, for other thing, we can simplify the code a bit and rely on exception handling for invalid lines. Speed is not the main motivation for this changes. However as I'm in the middle of benchmarking things we can see a small positive impact. Before: ! wall 0.009358 comb 0.000000 user 0.000000 sys 0.000000 (best of 303) After: ! wall 0.009173 comb 0.010000 user 0.010000 sys 0.000000 (best of 310)