Merge branch 'jc/maint-checkout-fix' into maint

* jc/maint-checkout-fix:
checkout: do not check out unmerged higher stages randomly

diff --combined builtin-checkout.c
index f6f8f086de980b5bc19ca59985a2b0d8201831d9,854401099410d5eeb590caf2ef56d4679ba77926..8e77767b49888aa2131088a810850dab7854594d
--- 1/builtin-checkout.c
--- 2/builtin-checkout.c
+++ b/builtin-checkout.c
@@@ -76,6 -76,15 +76,15 @@@ static int read_tree_some(struct tree *
        return 0;
  }
  
+ static int skip_same_name(struct cache_entry *ce, int pos)
+ {
+       while (++pos < active_nr &&
+              !strcmp(active_cache[pos]->name, ce->name))
+               ; /* skip */
+       return pos;
+ }
+ 
+ 
  static int checkout_paths(struct tree *source_tree, const char **pathspec)
  {
        int pos;
@@@ -107,6 -116,20 +116,20 @@@
        if (report_path_error(ps_matched, pathspec, 0))
                return 1;
  
+       /* Any unmerged paths? */
+       for (pos = 0; pos < active_nr; pos++) {
+               struct cache_entry *ce = active_cache[pos];
+               if (pathspec_match(pathspec, NULL, ce->name, 0)) {
+                       if (!ce_stage(ce))
+                               continue;
+                       errs = 1;
+                       error("path '%s' is unmerged", ce->name);
+                       pos = skip_same_name(ce, pos) - 1;
+               }
+       }
+       if (errs)
+               return 1;
+ 
        /* Now we are committed to check them out */
        memset(&state, 0, sizeof(state));
        state.force = 1;
@@@ -114,7 -137,11 +137,11 @@@
        for (pos = 0; pos < active_nr; pos++) {
                struct cache_entry *ce = active_cache[pos];
                if (pathspec_match(pathspec, NULL, ce->name, 0)) {
-                       errs |= checkout_entry(ce, &state, NULL);
+                       if (!ce_stage(ce)) {
+                               errs |= checkout_entry(ce, &state, NULL);
+                               continue;
+                       }
+                       pos = skip_same_name(ce, pos) - 1;
                }
        }
  
@@@ -386,11 -413,13 +413,11 @@@ static int switch_branches(struct check
        }
  
        /*
 -       * If the new thing isn't a branch and isn't HEAD and we're
 -       * not starting a new branch, and we want messages, and we
 -       * weren't on a branch, and we're moving to a new commit,
 -       * describe the old commit.
 +       * If we were on a detached HEAD, but we are now moving to
 +       * a new commit, we want to mention the old commit once more
 +       * to remind the user that it might be lost.
         */
 -      if (!new->path && strcmp(new->name, "HEAD") && !opts->new_branch &&
 -          !opts->quiet && !old.path && new->commit != old.commit)
 +      if (!opts->quiet && !old.path && new->commit != old.commit)
                describe_detached_head("Previous HEAD position was", old.commit);
  
        if (!old.commit) {

diff --combined t/t7201-co.sh
index 2e2b3bf53d75f587dd0823c8a82eaaf451c31607,83a366f1e7dcbe1d1678cadd87b9862713e82b97..fbec70d3c6abff4a97aa205aa10fbf6fe336fa5f
--- 1/t/t7201-co.sh
--- 2/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@@ -3,7 -3,7 +3,7 @@@
  # Copyright (c) 2006 Junio C Hamano
  #
  
 -test_description='git-checkout tests.
 +test_description='git checkout tests.
  
  Creates master, forks renamer and side branches from it.
  Test switching across them.
@@@ -337,4 -337,26 +337,26 @@@ test_expect_success 
      test refs/heads/delete-me = "$(git symbolic-ref HEAD)" &&
      test_must_fail git checkout --track -b track'
  
+ test_expect_success 'checkout an unmerged path should fail' '
+       rm -f .git/index &&
+       O=$(echo original | git hash-object -w --stdin) &&
+       A=$(echo ourside | git hash-object -w --stdin) &&
+       B=$(echo theirside | git hash-object -w --stdin) &&
+       (
+               echo "100644 $A 0       fild" &&
+               echo "100644 $O 1       file" &&
+               echo "100644 $A 2       file" &&
+               echo "100644 $B 3       file" &&
+               echo "100644 $A 0       filf"
+       ) | git update-index --index-info &&
+       echo "none of the above" >sample &&
+       cat sample >fild &&
+       cat sample >file &&
+       cat sample >filf &&
+       test_must_fail git checkout fild file filf &&
+       test_cmp sample fild &&
+       test_cmp sample filf &&
+       test_cmp sample file
+ '
+ 
  test_done