Can't install plugins from a branch (cordova@7)

$ cordova plugin add https://github.com/apache/cordova-plugins.git\#wkwebview-engine-localhost
Installing "cordova-labs-wkwebview-engine-localhost" for ios
Failed to install 'cordova-labs-wkwebview-engine-localhost': CordovaError: Failed to fetch plugin https://git-wip-us.apache.org/repos/asf/cordova-plugins.git#local-webserver via registry.
Probably this is either a connection problem, or plugin spec is incorrect.
Check your connection and plugin name/version/URL.
Error: npm: Command failed with exit code 254 Error output:
npm WARN package.json helloworld@1.0.0 No repository field.
npm WARN package.json helloworld@1.0.0 No README data
npm ERR! not a package /var/folders/40/pyxnqlcj6bn_43qrjp3p0xtw0000gp/T/npm-28533-ff14b1ee/git-wip-us.apache.org/repos/asf/cordova-plugins.git/local-webserver
npm ERR! Darwin 16.7.0
npm ERR! argv "/Users/shazron/.nvm/versions/node/v4.6.0/bin/node" "/Users/shazron/.nvm/versions/node/v4.6.0/bin/npm" "install" "https://git-wip-us.apache.org/repos/asf/cordova-plugins.git#local-webserver" "--save"
npm ERR! node v4.6.0
npm ERR! npm  v2.15.9
npm ERR! path /var/folders/40/pyxnqlcj6bn_43qrjp3p0xtw0000gp/T/npm-28533-ff14b1ee/unpack-968d75f9eab2/package.json
npm ERR! code ENOENT
npm ERR! errno -2
npm ERR! syscall open

npm ERR! enoent ENOENT: no such file or directory, open '/var/folders/40/pyxnqlcj6bn_43qrjp3p0xtw0000gp/T/npm-28533-ff14b1ee/unpack-968d75f9eab2/package.json'
npm ERR! enoent This is most likely not a problem with npm itself
npm ERR! enoent and is related to npm not being able to find a file.
npm ERR! enoent

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/shazron/Desktop/gtm/node_modules/npm-debug.log
    at /Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/fetch.js:205:33
    at _rejected (/Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:864:24)
    at /Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:890:30
    at Promise.when (/Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:1142:31)
    at Promise.promise.promiseDispatch (/Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:808:41)
    at /Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:624:44
    at runSingle (/Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:137:13)
    at flush (/Users/shazron/.nvm/versions/node/v4.6.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/cordova-fetch/node_modules/q/q.js:125:13)
    at nextTickCallbackWith0Args (node.js:420:9)
    at process._tickCallback (node.js:349:13)
Error: Failed to fetch plugin https://git-wip-us.apache.org/repos/asf/cordova-plugins.git#local-webserver via registry.
Probably this is either a connection problem, or plugin spec is incorrect.
Check your connection and plugin name/version/URL.
Error: npm: Command failed with exit code 254 Error output:
npm WARN package.json helloworld@1.0.0 No repository field.
npm WARN package.json helloworld@1.0.0 No README data
npm ERR! not a package /var/folders/40/pyxnqlcj6bn_43qrjp3p0xtw0000gp/T/npm-28533-ff14b1ee/git-wip-us.apache.org/repos/asf/cordova-plugins.git/local-webserver
npm ERR! Darwin 16.7.0
npm ERR! argv "/Users/shazron/.nvm/versions/node/v4.6.0/bin/node" "/Users/shazron/.nvm/versions/node/v4.6.0/bin/npm" "install" "https://git-wip-us.apache.org/repos/asf/cordova-plugins.git#local-webserver" "--save"
npm ERR! node v4.6.0
npm ERR! npm  v2.15.9
npm ERR! path /var/folders/40/pyxnqlcj6bn_43qrjp3p0xtw0000gp/T/npm-28533-ff14b1ee/unpack-968d75f9eab2/package.json
npm ERR! code ENOENT
npm ERR! errno -2
npm ERR! syscall open

npm ERR! enoent ENOENT: no such file or directory, open '/var/folders/40/pyxnqlcj6bn_43qrjp3p0xtw0000gp/T/npm-28533-ff14b1ee/unpack-968d75f9eab2/package.json'
npm ERR! enoent This is most likely not a problem with npm itself
npm ERR! enoent and is related to npm not being able to find a file.
npm ERR! enoent

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/shazron/Desktop/gtm/node_modules/npm-debug.log

Error: Failed to fetch plugin https://github.com/apache/cordova-plugins.git#wkwebview-engine-localhost via registry.
Probably this is either a connection problem, or plugin spec is incorrect.
Check your connection and plugin name/version/URL.
Failed to get absolute path to installed module