Build fails when context is mounted to /tmp

Actual behavior

Build fails when the context is mounted to /tmp

Expected behavior The build success regardless of where the context is mounted or the rules for mounting a context are documented

To Reproduce Steps to reproduce the behavior: IMAGE=gcr.io/kaniko-project/executor:793

This fails

docker run \
    -v  `pwd`/context:/tmp \
    $IMAGE \
          --context dir:///tmp/ \
          --dockerfile Dockerfile \
          -v trace \
          --no-push

This succeeds

docker run \
    -v  `pwd`/context:/workspace \
    $IMAGE \
          --context dir:///workspace/ \
          --dockerfile Dockerfile \
          -v trace \
          --no-push

Dockerfile used

FROM botpress/server:v12_0_0
RUN chmod -R gou+rw /botpress
WORKDIR /botpress

RUN apt-get update \
&& apt-get -y install curl gnupg \
&& curl -sL https://deb.nodesource.com/setup_11.x | bash \
&& apt-get -y install nodejs \
&& apt-get -y install rsync \
&& apt-get upgrade -y

RUN cd /botpress && npm install && npm install node-sp-auth --save-dev && npm install sp-request --save-dev && npm install activedirectory --save-dev

EXPOSE 3000-55000
CMD ["./bp"]

Additional Information

Dockerfile Please provide either the Dockerfile you're trying to build or one that can reproduce this error.
Build Context Please provide or clearly describe any files needed to build the Dockerfile (ADD/COPY commands)

Kaniko Image (fully qualified with digest)

Triage Notes for the Maintainers

Description	Yes/No
Please check if this a new feature you are proposing	- [ ]
Please check if the build works in docker but not in kaniko	- [ ]
Please check if this error is seen when you use `--cache` flag	- [ ]
Please check if your dockerfile is a multistage dockerfile	- [ ]

GoogleContainerTools / kaniko

Build fails when context is mounted to /tmp #999