Validator incorrectly ignores content after a non-leading comment marker

[rcjsuen]

FROM alpine
COPY 1.txt 2.txt \
 3.txt #4.txt /dir/

$ docker build .
Sending build context to Docker daemon  38.15MB
Step 1/2 : FROM alpine
 ---> e7d92cdc71fe
Step 2/2 : COPY 1.txt 2.txt  3.txt #4.txt /dir/
 ---> 7c0a78559869
Successfully built 7c0a78559869

$ docker run -v `pwd`/Dockerfile:/Dockerfile rcjsuen/dockerfile-utils lint /Dockerfile
Line: 3
 3.txt #4.txt /dir/
 ^^^^^
Error: When using COPY with more than one source file, the destination must be a directory and end with a / or a \

The #4.txt argument ends up causing it and all subsequent arguments to be ignored. The validator is then unable to find the /dir/ argument and flags a false warning.