Steps to reproduce by providing invalid URL [valid URL with HTTPS option]:
1) Task API from PostMan :

{
    "type": "import",
    "input": {
        "import_from": "https://xxxxxxxxxxxxxxx/log.qcow2",
        "import_from_format": "qcow2",
        "image_properties": {
            "disk_format": "qcow",
            "container_format": "bare",
            "name": "test-create2xxx"
        }
        
    }
}


Response from Task API :


{
    "status": "pending",
    "created_at": "2018-11-05T10:40:10Z",
    "updated_at": "2018-11-05T10:40:10Z",
    "self": "/v2/tasks/2d35894f-24a5-4ab6-8aba-3950008629e6",
    "result": null,
    "owner": "47441f261db046f9967ef099877369e4",
    "input": {
        "image_properties": {
            "container_format": "bare",
            "disk_format": "qcow",
            "name": "test-create2xxx"
        },
        "import_from_format": "qcow2",
        "import_from": "https://xxxxxxxxxxxxxxx/log.qcow2"
    },
    "message": "",
    "type": "import",
    "id": "2d35894f-24a5-4ab6-8aba-3950008629e6",
    "schema": "/v2/schemas/task"
}

2) Check the Task Progress :
{
    "status": "failure",
    "created_at": "2018-11-05T10:40:10Z",
    "updated_at": "2018-11-05T10:42:18Z",
    "expires_at": "2018-11-07T10:42:18Z",
    "self": "/v2/tasks/2d35894f-24a5-4ab6-8aba-3950008629e6",
    "result": null,
    "owner": "47441f261db046f9967ef099877369e4",
    "input": {
        "image_properties": {
            "container_format": "bare",
            "disk_format": "qcow",
            "name": "test-create2xxx"
        },
        "import_from_format": "qcow2",
        "import_from": "https://xxxxxxxxxxxxxxx/log.qcow2"
    },
    "message": "Task failed due to Internal Error",
    "type": "import",
    "id": "2d35894f-24a5-4ab6-8aba-3950008629e6",
    "schema": "/v2/schemas/task"
}


3) Log in to the VIM and view the Image :

[xxxx@undercloud (overcloudrc) ~]$ glance image-show 02503fd9-d29d-4d78-b31d-b6602a229ad1
+------------------+--------------------------------------+
| Property         | Value                                |
+------------------+--------------------------------------+
| checksum         | None                                 |
| container_format | bare                                 |
| created_at       | 2018-11-05T10:40:10Z                 |
| disk_format      | qcow                                 |
| id               | 02503fd9-d29d-4d78-b31d-b6602a229ad1 |
| locations        | []                                   |
| min_disk         | 0                                    |
| min_ram          | 0                                    |
| name             | test-create2xxx                      |
| owner            | 47441f261db046f9967ef099877369e4     |
| protected        | False                                |
| size             | None                                 |
| status           | saving                               |
| tags             | []                                   |
| updated_at       | 2018-11-05T10:40:10Z                 |
| virtual_size     | None                                 |
| visibility       | private                              |
+------------------+--------------------------------------+