rebase: ignore untracked files in submodules

An untracked file in a submodule should not prevent a rebase from
starting.  Even if the submodule's SHA is changed, and that file would
conflict with a new tracked file, it's still OK to start the rebase
and discover the conflict later.

Signed-off-by: David Turner <dturner@twosigma.com>

src/rebase.c

@@ -546,7 +546,9 @@ static int rebase_ensure_not_dirty(
 	}
 
 	if (check_workdir) {
-		if ((error = git_diff_index_to_workdir(&diff, repo, index, NULL)) < 0)
+		git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+		diff_opts.ignore_submodules = GIT_SUBMODULE_IGNORE_UNTRACKED;
+		if ((error = git_diff_index_to_workdir(&diff, repo, index, &diff_opts)) < 0)
 			goto done;
 
 		if (git_diff_num_deltas(diff) > 0) {

tests/rebase/submodule.c

@@ -0,0 +1,65 @@
+#include "clar_libgit2.h"
+#include "git2/checkout.h"
+#include "git2/rebase.h"
+#include "posix.h"
+#include "signature.h"
+
+#include <fcntl.h>
+
+static git_repository *repo;
+static git_signature *signature;
+
+// Fixture setup and teardown
+void test_rebase_submodule__initialize(void)
+{
+	repo = cl_git_sandbox_init("rebase-submodule");
+	cl_git_pass(git_signature_new(&signature,
+		"Rebaser", "rebaser@rebaser.rb", 1405694510, 0));
+}
+
+void test_rebase_submodule__cleanup(void)
+{
+	git_signature_free(signature);
+	cl_git_sandbox_cleanup();
+}
+
+void test_rebase_submodule__init_untracked(void)
+{
+	git_rebase *rebase;
+	git_reference *branch_ref, *upstream_ref;
+	git_annotated_commit *branch_head, *upstream_head;
+	git_buf untracked_path = GIT_BUF_INIT;
+	FILE *fp;
+	git_submodule *submodule;
+	git_config *config;
+
+	cl_git_pass(git_reference_lookup(&branch_ref, repo, "refs/heads/asparagus"));
+	cl_git_pass(git_reference_lookup(&upstream_ref, repo, "refs/heads/master"));
+
+	cl_git_pass(git_annotated_commit_from_ref(&branch_head, repo, branch_ref));
+	cl_git_pass(git_annotated_commit_from_ref(&upstream_head, repo, upstream_ref));
+
+	git_repository_config(&config, repo);
+
+	cl_git_pass(git_config_set_string(config, "submodule.my-submodule.url", git_repository_path(repo)));
+
+	git_config_free(config);
+
+	cl_git_pass(git_submodule_lookup(&submodule, repo, "my-submodule"));
+	cl_git_pass(git_submodule_update(submodule, 1, NULL));
+
+	git_buf_printf(&untracked_path, "%s/my-submodule/untracked", git_repository_workdir(repo));
+	fp = fopen(git_buf_cstr(&untracked_path), "w");
+	fprintf(fp, "An untracked file in a submodule should not block a rebase\n");
+	fclose(fp);
+	git_buf_free(&untracked_path);
+
+	cl_git_pass(git_rebase_init(&rebase, repo, branch_head, upstream_head, NULL, NULL));
+
+	git_submodule_free(submodule);
+	git_annotated_commit_free(branch_head);
+	git_annotated_commit_free(upstream_head);
+	git_reference_free(branch_ref);
+	git_reference_free(upstream_ref);
+	git_rebase_free(rebase);
+}

tests/resources/rebase-submodule/my-submodule

@@ -0,0 +1 @@
+Subproject commit efad0b11c47cb2f0220cbd6f5b0f93bb99064b00