Merge branch 'dg/local-mod-error-messages'

* dg/local-mod-error-messages:
t7609: test merge and checkout error messages
unpack_trees: group error messages by type
merge-recursive: distinguish "removed" and "overwritten" messages
merge-recursive: porcelain messages for checkout
Turn unpack_trees_options.msgs into an array + enum

Conflicts:
t/t3400-rebase.sh

diff --cc builtin/checkout.c
Simple merge

diff --cc merge-recursive.c
Simple merge

diff --cc t/t3400-rebase.sh
index a19aeb6441cb29dc20478cf898b5f7767d770c94,45ef28281512e8f53eafc3cb23c1b99e0ef82c0f..349eebd54268c927249322dc22fc478869860f7c
--- 1/t/t3400-rebase.sh
--- 2/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@@ -151,9 -127,10 +151,10 @@@ test_expect_success 'setup: recover' 
  '
  
  test_expect_success 'Show verbose error when HEAD could not be detached' '
 -     : > B &&
 -     test_must_fail git rebase topic 2> output.err > output.out &&
 -     grep "The following untracked working tree files would be overwritten by checkout:" output.err &&
 -     grep B output.err
 +      >B &&
 +      test_must_fail git rebase topic 2>output.err >output.out &&
-       grep "Untracked working tree file .B. would be overwritten" output.err
++      grep "The following untracked working tree files would be overwritten by checkout:" output.err &&
++      grep B output.err
  '
  rm -f B
  

diff --cc t/t3404-rebase-interactive.sh
Simple merge

diff --cc unpack-trees.c
Simple merge