rebase::abort: test we can abort rebase by revspec

Test that we can properly abort a rebase when it is initialized by a
revspec.  This ensures that we do not conflate revspecs and refnames.

tests/rebase/abort.c

@@ -145,6 +145,25 @@ void test_rebase_abort__merge_by_id(void)
 	git_rebase_free(rebase);
 }
 
+void test_rebase_abort__merge_by_revspec(void)
+{
+	git_rebase *rebase;
+	git_annotated_commit *branch_head, *onto_head;
+
+	cl_git_pass(git_annotated_commit_from_revspec(&branch_head, repo, "b146bd7"));
+	cl_git_pass(git_annotated_commit_from_revspec(&onto_head, repo, "efad0b1"));
+	
+	cl_git_pass(git_rebase_init(&rebase, repo, branch_head, NULL, onto_head, NULL));
+	cl_assert_equal_i(GIT_REPOSITORY_STATE_REBASE_MERGE, git_repository_state(repo));
+
+	test_abort(branch_head, onto_head);
+
+	git_annotated_commit_free(branch_head);
+	git_annotated_commit_free(onto_head);
+
+	git_rebase_free(rebase);
+}
+
 void test_rebase_abort__merge_by_id_immediately_after_init(void)
 {
 	git_rebase *rebase;