Merge branch 'pw/apply-ulong-overflow-check'

"git apply" internally uses unsigned long for line numbers and uses
strtoul() to parse numbers on the hunk headers.  It however forgot
to check parse errors.

* pw/apply-ulong-overflow-check:
  apply: detect overflow when parsing hunk header

diff --cc apply.c
Simple merge

diff --cc t/t4100-apply-stat.sh
Simple merge