Removed a duplicate constant.

tests/t10-refs.c

@@ -59,7 +59,6 @@ BEGIN_TEST("readtag", non_existing_tag_reference_looking_up)
 	git_repository_free(repo);
 END_TEST
 
-static const char *head_ref_name = "HEAD";
 static const char *head_tracker_sym_ref_name = "head-tracker";
 static const char *current_head_target = "refs/heads/master";
 static const char *current_master_tip = "be3563ae3f795b2b4353bcce3a527ad0a4f7f644";
@@ -72,10 +71,10 @@ BEGIN_TEST("readsymref", symbolic_reference_looking_up)
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 
-	must_pass(git_repository_lookup_ref(&reference, repo, head_ref_name));
+	must_pass(git_repository_lookup_ref(&reference, repo, GIT_HEAD_FILE));
 	must_be_true(reference->type & GIT_REF_SYMBOLIC);
 	must_be_true((reference->type & GIT_REF_PACKED) == 0);
-	must_be_true(strcmp(reference->name, head_ref_name) == 0);
+	must_be_true(strcmp(reference->name, GIT_HEAD_FILE) == 0);
 
 	must_pass(git_reference_resolve(&resolved_ref, reference));
 	must_be_true(resolved_ref->type == GIT_REF_OID);
@@ -126,7 +125,7 @@ BEGIN_TEST("readsymref", looking_up_head_then_master)
 	must_pass(git_reference_resolve(&resolved_ref, reference));
 	comp_base_ref = resolved_ref;
 
-	must_pass(git_repository_lookup_ref(&reference, repo, head_ref_name));
+	must_pass(git_repository_lookup_ref(&reference, repo, GIT_HEAD_FILE));
 	must_pass(git_reference_resolve(&resolved_ref, reference));
 	must_pass(git_oid_cmp(git_reference_oid(comp_base_ref), git_reference_oid(resolved_ref)));
 
@@ -144,7 +143,7 @@ BEGIN_TEST("readsymref", looking_up_master_then_head)
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
 
 	must_pass(git_repository_lookup_ref(&master_ref, repo, current_head_target));
-	must_pass(git_repository_lookup_ref(&reference, repo, head_ref_name));
+	must_pass(git_repository_lookup_ref(&reference, repo, GIT_HEAD_FILE));
 
 	must_pass(git_reference_resolve(&resolved_ref, reference));
 	must_pass(git_oid_cmp(git_reference_oid(master_ref), git_reference_oid(resolved_ref)));