Escape character that follows a label can cause parsing issues

[rcjsuen]

The first Dockerfile is fine but the second one is not. Looks like the \ following the label immediately is the cause of this bug.

FROM scratch
LABEL "a"="b" \
    "c"="d"

FROM scratch
LABEL "a"="b"\
    "c"="d"

$ dockerfile-utils lint Dockerfile 
Line: 3
    "c"="d"
       ^^^^
Error: LABEL names can not be blank

$ docker build .
Sending build context to Docker daemon     47MB
Step 1/2 : FROM scratch
 ---> 
Step 2/2 : LABEL "a"="b"    "c"="d"
 ---> Running in c1d90c5f7985
Removing intermediate container c1d90c5f7985
 ---> bdff47f2a0a5
Successfully built bdff47f2a0a5