Merge branch 'tr/line-log'

Fix "log -L" command line parsing bugs.

* tr/line-log:
  t4211: fix incorrect rebase at f8395edc (range-set: satisfy non-empty ranges invariant)
  line-log: fix "log -LN" crash when N is last line of file
  range-set: satisfy non-empty ranges invariant
  t4211: demonstrate crash when first -L encountered is empty range
  t4211: demonstrate empty -L range crash
  range-set: fix sort_and_merge_range_set() corner case bug