Build fails when context is mounted to /tmp

[cvgw]

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

[cvgw]

related to #793