Merge branch 'jn/scripts-updates' into pu

I'll need to poke Paulus and Pat with the two subsystem patches
but other than that they looked all fairly straight-forward.

* jn/scripts-updates:
  remove #!interpreter line from shell libraries
  test: replace shebangs with descriptions in shell libraries
  test: make FILEMODE a lazy prereq
  contrib: remove git-p4import
  gitk: chmod +x po2msg
  git-gui: chmod +x po2msg, windows/git-gui.sh
  mark contributed hooks executable
  mark perl test scripts executable
  mark Windows build scripts executable
Merge branch 'aa/transport-non-positive-depth-only' into pu

* aa/transport-non-positive-depth-only:
  transport: catch non positive --depth option value