🐛 Source S3: tab delimiter is not parsed properly

[alafanechere]

Environment

• Source Connector and version: Source S3 0.1.7
• Severity: Critical
• Step where error happened: Sync job

Current Behavior

When dealing with CSV file, the S3 source connector is not parsing the /t character in the delimiter field properly.
It leads to the following error during sync

ValueError: only single character unicode strings can be converted to Py_UCS4, got length 4

The user provided the config blob stored in Postgres when they are using \t:

{
    "name": "s3_my_data_tsv",
    "sourceId": "3d7c5081-0624-47ab-8033-fd3e2dd0e5be",
    "tombstone": false,
    "workspaceId": "f5918909-d769-4482-b45b-d95e38befcc9",
    "configuration": {
        "format": {
            "filetype": "csv",
            "delimiter": "\\t",
            "block_size": 10000,
            "quote_char": "\"",
            "escape_char": "\\",
            "double_quote": true,
            "advanced_options": "{\"column_names\": [\"filename\", \"email\", \"locale\", \"updated_ts\"]}",
            "newlines_in_values": false,
            "additional_reader_options": "{}"
        },
        "schema": "{\"filename\": \"string\", \"email\": \"string\", \"locale\": \"string\", \"updated_ts\": \"string\"}",
        "dataset": "my_data_tsv",
        "provider": {
            "bucket": "my_bucket",
            "endpoint": "",
            "path_prefix": "manual/2021-12-03/",
            "aws_access_key_id": "***",
            "aws_secret_access_key": "***"
        },
        "path_pattern": "manual/2021-12-03/*.tsv"
    },
    "sourceDefinitionId": "69589781-7828-43c5-9f63-8925b1c1ccc2"
}

The delimiter is stored as \\t and not \t.

Manually editing the config blob in Postgres to set \t solved the issue.

Expected Behavior

Tab separated value files should be correctly parsed by the S3 source connector.

Steps to Reproduce

1. Upload a .tsv file to S3
2. Set up an S3 source with a \t delimiter value
3. Set up a connection between this source and a destination
4. Run the sync