protoc returned a line we do not understand: Backslashes, consecutive slashes, \".\", or \"..\" are not allowed in the virtual path"

[michaelrbock]

Hi, when running prototool lint I get the following error which asks for an issue to be reported:

WARN    protoc returned a line we do not understand, please file this as an issue at https://github.com/uber/prototool/issues/new       {"protocLine": "./b.pr
oto: Backslashes, consecutive slashes, \".\", or \"..\" are not allowed in the virtual path"}