Tried to switch from 2.5.0 to 2.7.0

[webpack-bot]

Do you want to request a feature or report a bug?
Seems to be a bug or requires slightly different configuration.

What is the current behavior?
When using 2.7.0 I cannot connect to the sockjs-node since it uses a path with two slashes in it.
//sockjs-node instead of /sockjs-node.

If the current behavior is a bug, please provide the steps to reproduce.
Seems to be a bug switching back to 2.5.0 makes it work right away.
Seems to be related to how client now calculates the socket path not removing a single /

What is the expected behavior?
Both 2.5.0 and 2.7.0 should work the same regarding this part.
Since this didn't work I didn't investigate further but my proxies also seemed affected.

If this is a feature request, what is motivation or use case for changing the behavior?
I think it's broken, but maybe it's a new requirement in the config.

Please mention other relevant information such as the browser version, Node.js version, webpack version and Operating System.
I am using 6.11 node.
Mac OS X 10.12.6

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This issue was moved from webpack/webpack#5464 by @sokra. Orginal issue was by @richtera.

[dylansmith]

2.7.0 appears to have been unpublished from npm.

[shellscape]

2.7.0 was unpublished due to an uncaught regression. Please use 2.7.1 instead.

[richtera]

Checked 2.7.1 works :)