fsck.vfat when invoked from fsck acts as if -N was specified

[LukeKendall]

fsck.vfat's non-interactive mode is interactive, which leads to serious confusion and frustration for the user.

When you run fsck on a vfat partition, fsck.vfat runs interactively, prompting the user to make various choices, and acting on them. then, at the end, it reports
    "Leaving filesystem unchanged."
and fails to apply the corrections.

The fsck.vfat man page says:
"Note: If -a and -r are absent, the filesystem is only checked, but not repaired."

One might think that the bug is in fsck, failing to invoke fsck.vfat with -r (interactive mode) by default,
but in my view the error is in fsck.vfat, in that it runs in interactive mode to all appearances, with no way for the user to discover that although it was interacting with them, *it* considers itself not to have been in "interactive mode".

It would also be nice if fsck.vfat reported it was running in check-only mode (-n?) when invoked with no arguments, even if it is not otherwise changed, and continues to work as it currently does, apparently interacting with the user (in this strangely interactive non-interactive mode, with -r not specified). It would be nice if such a message was provided both at the start of fsck.vfat's output (to warn the user in advance), as well as at the end (in case the initial message has scrolled off and/or is unreachable).

If fsck.vfat's default mode is a check-only mode, then perhaps the fsck program also needs to be modified to explicitly use "-r" unless *it* has been invoked with "-N".

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: dosfstools 3.0.26-1
ProcVersionSignature: Ubuntu 3.13.0-57.95-generic 3.13.11-ckt21
Uname: Linux 3.13.0-57-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.11
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Aug 2 16:24:04 2015
Dependencies:
 gcc-4.9-base 4.9.1-0ubuntu1
 libc6 2.19-0ubuntu6.6
 libgcc1 1:4.9.1-0ubuntu1
 multiarch-support 2.19-0ubuntu6.6
InstallationDate: Installed on 2014-01-24 (554 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140123)
SourcePackage: dosfstools
UpgradeStatus: No upgrade log present (probably fresh install)