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)
Test issue2761
$ hg init
$ touch to-be-deleted
$ hg add
adding to-be-deleted
$ hg ci -m first
$ echo a > to-be-deleted
$ hg ci -m second
$ rm to-be-deleted
$ hg diff -r 0
Same issue, different code path
$ hg up -C
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch does-not-exist-in-1
$ hg add
adding does-not-exist-in-1
$ hg ci -m third
$ rm does-not-exist-in-1
$ hg diff -r 1