Merge branch 'lf/setup-prefix-pathspec' into maint

"git cmd -- ':(top'" was not diagnosed as an invalid syntax, and
instead the parser kept reading beyond the end of the string.

* lf/setup-prefix-pathspec:
  setup.c: check that the pathspec magic ends with ")"
  setup.c: stop prefix_pathspec() from looping past the end of string

diff --cc setup.c
Simple merge