Fix bisect script run and level validators

app/src/test/java/solutions/tretter/githugandroid/GitSandboxEngineTest.kt

@@ -504,6 +504,37 @@ class GitSandboxEngineTest {
         }
     }
 
+    @Test
+    fun nativeBisectRunScriptShortcutRunsThroughShell() {
+        val git = testGitBinary()
+        assumeTrue(git.exists() && git.canExecute())
+        val root = Files.createTempDirectory("githug-bisect-run-script").toFile()
+        try {
+            val runtime = GitRepositoryRuntime(root, git)
+            val level = bisectLevel()
+            var repo = runtime.prepareLevel(level)
+
+            listOf(
+                "git bisect start",
+                "git bisect bad HEAD",
+                "git bisect good known-good",
+            ).forEach { command ->
+                val (nextRepo, _) = runtime.execute(level, repo, command)
+                repo = nextRepo
+            }
+
+            val (_, output) = runtime.execute(level, repo, "git bisect run ./test-balance.sh")
+            val text = output.joinToString("\n")
+
+            assertFalse(text, text.contains("Permission denied", ignoreCase = true))
+            assertFalse(text, text.contains("can't execute", ignoreCase = true))
+            assertFalse(text, text.contains("bogus exit code", ignoreCase = true))
+            assertTrue(text, text.contains("first bad commit", ignoreCase = true))
+        } finally {
+            root.deleteRecursively()
+        }
+    }
+
     private fun testGitBinary(): File {
         System.getenv("GITHUG_TEST_GIT_BINARY")
             ?.takeIf { it.isNotBlank() }