git bashで docker -w /usr/src/projectが失敗

git bashで、Docker run -vや -wが "working directory ... invalid"になる

$ docker run --rm -v /e/work/project:/usr/src/project -w /usr/src/project ruby:2.3.0 bundle init
CProgram Files\Docker\Docker\Resources\bin\docker.exe: Error response from daemon: the working directory 'C:/Program Files/Git/usr/src/project' is invalid, it needs to be an absolute path

環境

Windows10 Enterprise
git bash
docker version : 17.12.0-ce, build c97c6d6

パスの前の / を重ねることで解決。

$ docker run --rm -v //e/work/project://usr/src/project -w //usr/src/project ruby:2.3.0 bundle init
Writing new Gemfile to /usr/src/project/Gemfile

参照

Problem with -v shared folders in 1.6