filepathfilter: don't say file is both accepted and rejected

The file path filter can mark a file as either accepted or rejected.
However, one of the messages that says that a file was rejected is in
the main code path, and is therefore always executed, even if the file
is actually accepted.  This leads to contradictory messages and noisier
output.

Ensure that we indicate that a file is rejected by the filter only if it
is indeed rejected; otherwise, say only that it is accepted.

filepathfilter/filepathfilter.go

@@ -61,8 +61,8 @@ func (f *Filter) Allows(filename string) bool {
		}
	}

	tracerx.Printf("filepathfilter: rejecting %q via %v", filename, f.include)
	if !included && len(f.include) > 0 {
		tracerx.Printf("filepathfilter: rejecting %q via %v", filename, f.include)
		return false
	}

t/t-checkout.sh

@@ -41,13 +41,15 @@ begin_test "checkout"
  rm -rf file1.dat file2.dat file3.dat folder1/nested.dat folder2/nested.dat

  echo "checkout should replace all"
  git lfs checkout 2>&1 | tee checkout.log
  GIT_TRACE=1 git lfs checkout 2>&1 | tee checkout.log
  [ "$contents" = "$(cat file1.dat)" ]
  [ "$contents" = "$(cat file2.dat)" ]
  [ "$contents" = "$(cat file3.dat)" ]
  [ "$contents" = "$(cat folder1/nested.dat)" ]
  [ "$contents" = "$(cat folder2/nested.dat)" ]
  grep "Checking out LFS objects: 100% (5/5), 95 B" checkout.log
  grep 'accepting "file1.dat"' checkout.log
  ! grep 'rejecting "file1.dat"' checkout.log

  # Remove the working directory
  rm -rf file1.dat file2.dat file3.dat folder1/nested.dat folder2/nested.dat