Merge branch 'jk/portable'

* jk/portable:
  t6000lib: re-fix tr portability
  t7505: use SHELL_PATH in hook
  t9112: add missing #!/bin/sh header
  filter-branch: use $SHELL_PATH instead of 'sh'
  filter-branch: don't use xargs -0
  add NO_EXTERNAL_GREP build option
  t6000lib: tr portability fix
  t4020: don't use grep -a
  add test_cmp function for test scripts
  remove use of "tail -n 1" and "tail -1"
  grep portability fix: don't use "-e" or "-q"
  more tr portability test script fixes
  t0050: perl portability fix
  tr portability fixes

diff --cc git-submodule.sh
Simple merge

diff --cc t/t4201-shortlog.sh
index eef4cafda99729977af9bee2eca83493814faede,91ea69631472d9a13184a58a41a55277746b1498..672b28859f0612ec7eef15765ccdb006beac27e6
--- 1/t/t4201-shortlog.sh
--- 2/t/t4201-shortlog.sh
+++ b/t/t4201-shortlog.sh
@@@ -45,11 -45,6 +45,11 @@@ A U Thor (5)
  
  EOF
  
- test_expect_success 'shortlog wrapping' 'diff -u expect out'
+ test_expect_success 'shortlog wrapping' 'test_cmp expect out'
  
 +git log HEAD > log
 +GIT_DIR=non-existing git shortlog -w < log > out
 +
 +test_expect_success 'shortlog from non-git directory' 'diff -u expect out'
 +
  test_done