Fix invalid escape sequence (#1675)
Fix invalid escape sequence (#1675)

The backslash used for Windows paths needs to be escaped itself. This was okay because `\{` is an invalid escape sequence which was ignored; but now they'll throw errors due to https://github.com/bazelbuild/bazel/commit/73402fa4aa5b9de46c9a4042b75e6fb332ad4a7f.
bazelbuild/rules_docker,bazelbuild/rules_docker,bazelbuild/rules_docker,bazelbuild/rules_docker