Incomplete read but requests did not raise an error

First, let me preface that this issue might be because of some misspecification on the server side, but I'm curious if anyone has any ideas here. This [URL](https://hazards.fema.gov/femaportal/NFHL/Download/ProductsDownLoadServlet?DFIRMID=10001C&state=DELAWARE&county=KENT%20COUNTY&fileName=10001C_20190130.zip)  points to a zip file I'd like to download. If I paste the URL in a browser window or `wget`, I successfully manage to download the zip file but I'm unable to download the zip file using `requests` or more accurately, `requests` only downloads a portion of the file and does not raise an error.

## Expected Result

Wanting to do this in python, I used `requests` and I had logic to stream the content and  `iter_content` from the response and write to a file. I expected to write to and create a ~67 MB zipfile, or raise an incomplete read error.

## Actual Result

The response content is only `2583` bytes but it did successfully redirect to the right URL.

## Reproduction Steps

 Simple code with outputs to replicate:
```
>>> import requests
>>> url = 'https://hazards.fema.gov/femaportal/NFHL/Download/ProductsDownLoadServlet?DFIRMID=10001C&state=DELAWARE&county=KENT%20COUNTY&fileName=10001C_20190130.zip'
>>> resp = requests.get(url)
>>> len(resp.content)
2583
>>> resp.headers['content-length']
'66892906'
>>> resp.url
'https://hazards.fema.gov/nfhlv2/output/County/10001C_20190130.zip'
```
Anecdotally, I used a relatively old [`wget`](https://pypi.org/project/wget/) package (which it looks like is just using `urllib`) and it gave me an incomplete read error.
```
>>> wget.download('https://hazards.fema.gov/nfhlv2/output/County/10001C_20190130.zip')
  0% [                                                                        ]     8192 / 66892906Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.7/site-packages/wget.py", line 526, in download
    (tmpfile, headers) = ulib.urlretrieve(binurl, tmpfile, callback)
  File "/usr/local/lib/python3.7/urllib/request.py", line 288, in urlretrieve
    % (read, size), result)
urllib.error.ContentTooShortError: <urlopen error retrieval incomplete: got only 2583 out of 66892906 bytes>
```

## System Information

    $ python -m requests.help

```
{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": "2.6.1"
  },
  "idna": {
    "version": "2.8"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.7.3"
  },
  "platform": {
    "release": "4.9.125-linuxkit",
    "system": "Linux"
  },
  "pyOpenSSL": {
    "openssl_version": "1010102f",
    "version": "19.0.0"
  },
  "requests": {
    "version": "2.21.0"
  },
  "system_ssl": {
    "version": "101000af"
  },
  "urllib3": {
    "version": "1.24.3"
  },
  "using_pyopenssl": true
}
```


**Update**: This might be related to the fact that I was running this in a `docker` container. When I run it outside of a `docker` container, it works as expected:
```
Python 3.7.3 (default, May 10 2019, 15:15:13)
[Clang 10.0.1 (clang-1001.0.46.3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests
>>> requests.__version__
'2.21.0'
>>> url = 'https://hazards.fema.gov/nfhlv2/output/County/10001C_20190130.zip'
>>> r = requests.get(url)
>>> len(r.content)
66892906
```

and outside of my docker container, this is the system info:
```
{
  "chardet": {
    "version": "3.0.4"
  },
  "cryptography": {
    "version": ""
  },
  "idna": {
    "version": "2.8"
  },
  "implementation": {
    "name": "CPython",
    "version": "3.7.3"
  },
  "platform": {
    "release": "18.5.0",
    "system": "Darwin"
  },
  "pyOpenSSL": {
    "openssl_version": "",
    "version": null
  },
  "requests": {
    "version": "2.21.0"
  },
  "system_ssl": {
    "version": "1000213f"
  },
  "urllib3": {
    "version": "1.24.3"
  },
  "using_pyopenssl": false
}
```

This is an issue in urllib3 (urllib3/urllib3#723) that's technically been patched but is considered breaking in Requests. We have a PR (#3563) merged to address the issue but it's on hold until the next major version of Requests.