For topologies before 1.4 manage qemu missing

If qemu is missing for topologies before 1.4 we try
to search it in the path.

Ref #921

tests/modules/qemu/test_qemu_vm.py

@@ -85,6 +85,22 @@ def test_vm(project, manager, fake_qemu_binary):
     assert vm.id == "00010203-0405-0607-0809-0a0b0c0d0e0f"
 
 
+def test_vm_invalid_qemu_with_platform(project, manager, fake_qemu_binary):
+
+    vm = QemuVM("test", "00010203-0405-0607-0809-0a0b0c0d0e0f", project, manager, qemu_path="/usr/fake/bin/qemu-system-64", platform="x86_64")
+
+    assert vm.qemu_path == fake_qemu_binary
+    assert vm.platform == "x86_64"
+
+
+def test_vm_invalid_qemu_without_platform(project, manager, fake_qemu_binary):
+
+    vm = QemuVM("test", "00010203-0405-0607-0809-0a0b0c0d0e0f", project, manager, qemu_path="/usr/fake/bin/qemu-system-x86_64")
+
+    assert vm.qemu_path == fake_qemu_binary
+    assert vm.platform == "x86_64"
+
+
 def test_is_running(vm, running_subprocess_mock):
 
     vm._process = None
@@ -270,7 +286,6 @@ def test_set_qemu_path_old_windows(vm, tmpdir):
     assert vm.platform == "i386"
 
 
-
 @pytest.mark.skipif(sys.platform.startswith("win"), reason="Not supported on Windows")
 def test_set_qemu_path_kvm_binary(vm, tmpdir, fake_qemu_binary):