Fails to download an image from e-hentai when remote file name is exactly "509.gif"

[i-rinat]

If remote file name is literally "509.gif", limit detector in e-hentai/exhentai extractor triggers and stops.

Example (NSFW):

$ gallery-dl -v 'https://e-hentai.org/s/69655771ba/726894-510'
[gallery-dl][debug] Version 1.23.0
[gallery-dl][debug] Python 3.10.6 - Linux-5.18.0-4-amd64-x86_64-with-glibc2.34
[gallery-dl][debug] requests 2.27.1 - urllib3 1.26.9
[gallery-dl][debug] Starting DownloadJob for 'https://e-hentai.org/s/69655771ba/726894-510'
[exhentai][debug] Using ExhentaiGalleryExtractor for 'https://e-hentai.org/s/69655771ba/726894-510'
[exhentai][info] no username given; using e-hentai.org
[urllib3.connectionpool][debug] Starting new HTTPS connection (1): e-hentai.org:443
[urllib3.connectionpool][debug] https://e-hentai.org:443 "GET /s/69655771ba/726894-510 HTTP/1.1" 200 1578
[exhentai][debug] Sleeping for 4.999 seconds
[urllib3.connectionpool][debug] https://e-hentai.org:443 "GET /g/726894/71bc9e38d2/ HTTP/1.1" 200 6725
[exhentai][error] Image limit reached! Continue with 'https://e-hentai.org/s/69655771ba/726894-510' as URL after resetting it.
$