AbstractFileSystem.exists() catches every exception

[tfelbr]

Hello,

I would like to kindly request a change in the implementation of AbstractFileSystem.exists(), as it currently catches every exception that might get thrown without any notice. An in my opinion better approach would be something like this:

def exists(self, path, **kwargs):
    try:
        self.info(path, **kwargs)
        return True
    except FileNotFoundError:
        return False
    except Exception as e:
        logging.warning(e)
        return False

This would preserve the current compatibility while still showing thrown exceptions as a warning.

[martindurant]

Warnings are only really useful if they imply a user can meaningfully act on them - which would not be the case here. Perhaps a logging call would be apropriate.

Note that it is not, in general, possible to know whether a file cannot be reached right now or if indeed it doesn't exist, especially with backends that don't have formal listing capabilities (e.g., HTTP). That means that we must interpret any number of IO and parsing-related exceptions as non-existence, in the sense that the path points to content we cannot read.