Running tileserver-php via Docker on Windows using a bind mount volume makes filemtime() return 0

[jbaranski]

If filemtime returns 0, the ETag hash is always the same and therefore every file attempted to serve 304's.

If filemtime is run on any file inside the container that's not part of the host mount volume (like /start.sh) it returns the correct value.

Any thoughts on the best way to resolve this? Here are a couple ideas:

• Modify your code to check a flag and short circuit the isModified function if set, (HTTP_IF_MODIFIED_SINCE or HTTP_IF_NONE_MATCH could be set to SKIP or EXIT in .htaccess instead of an actual timestamp)
• If lastModifiedTime in isModified is 0 don't set any headers, skip out and return false

If you have any other ideas I'd like to hear them, I would be happy to put together an MR based on what you want to do.