plugin add not working on cordova 7

executing

root@nodejs-512mb-nyc3-01:~/test3# cordova -v
7.0.1

root@nodejs-512mb-nyc3-01:~/test# cordova plugin add https://github.com/alongubkin/phonertc.git

Error: Failed to fetch plugin https://github.com/alongubkin/phonertc.git 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 235 Error output:
npm ERR! addLocal Could not install /tmp/npm-2592-47e4a1f6/git-cache-571e9d74/fed3028ca05d87f04a1b82ebab410f4707c554f5
npm ERR! Linux 4.4.0-79-generic
npm ERR! argv "/usr/bin/nodejs" "/usr/bin/npm" "install" "https://github.com/alongubkin/phonertc.git" "--save"
npm ERR! node v6.11.0
npm ERR! npm v3.10.10
npm ERR! code EISDIR
npm ERR! errno -21
npm ERR! syscall read

npm ERR! eisdir EISDIR: illegal operation on a directory, read
npm ERR! eisdir This is most likely not a problem with npm itself
npm ERR! eisdir and is related to npm not being able to find a package.json in
npm ERR! eisdir a package you are trying to install.

npm ERR! Please include the following file with any support request:
npm ERR! /root/test3/node_modules/npm-debug.log

npm-debug.log File:

` info it worked if it ends with ok
1 verbose cli [ '/usr/bin/nodejs',
1 verbose cli '/usr/bin/npm',
1 verbose cli 'install',
1 verbose cli 'https://github.com/alongubkin/phonertc.git',
1 verbose cli '--save' ]
2 info using npm@3.10.10
3 info using node@v6.11.0
4 silly loadCurrentTree Starting
5 silly install loadCurrentTree
6 silly install readLocalPackageData
7 silly fetchPackageMetaData https://github.com/alongubkin/phonertc.git
8 silly fetchOtherPackageData https://github.com/alongubkin/phonertc.git
9 silly cache add args [ 'https://github.com/alongubkin/phonertc.git', null ]
10 verbose cache add spec https://github.com/alongubkin/phonertc.git
11 silly cache add parsed spec Result {
11 silly cache add raw: 'https://github.com/alongubkin/phonertc.git',
11 silly cache add scope: null,
11 silly cache add escapedName: null,
11 silly cache add name: null,
11 silly cache add rawSpec: 'https://github.com/alongubkin/phonertc.git',
11 silly cache add spec: 'git+https://github.com/alongubkin/phonertc.git',
11 silly cache add type: 'hosted',
11 silly cache add hosted:
11 silly cache add { type: 'github',
11 silly cache add ssh: 'git@github.com:alongubkin/phonertc.git',
11 silly cache add sshUrl: 'git+ssh://git@github.com/alongubkin/phonertc.git',
11 silly cache add httpsUrl: 'git+https://github.com/alongubkin/phonertc.git',
11 silly cache add gitUrl: 'git://github.com/alongubkin/phonertc.git',
11 silly cache add shortcut: 'github:alongubkin/phonertc',
11 silly cache add directUrl: 'https://raw.githubusercontent.com/alongubkin/phonertc/master/package.json' } }
12 verbose addRemoteGit caching https://github.com/alongubkin/phonertc.git
13 verbose addRemoteGit git+https://github.com/alongubkin/phonertc.git is a repository hosted by github
14 silly tryClone cloning git+https://github.com/alongubkin/phonertc.git via git+https://github.com/alongubkin/phonertc.git
15 verbose tryClone git-https-github-com-alongubkin-phonertc-git-4a59f58b not in flight; caching
16 verbose correctMkdir /root/.npm/_git-remotes correctMkdir not in flight; initializing
17 verbose makeDirectory /root/.npm/_git-remotes creation not in flight; initializing
18 silly makeDirectory /root/.npm/_git-remotes uid: 0 gid: 0
19 info git [ 'clone',
19 info git '--template=/root/.npm/_git-remotes/_templates',
19 info git '--mirror',
19 info git 'https://github.com/alongubkin/phonertc.git',
19 info git '/root/.npm/_git-remotes/git-https-github-com-alongubkin-phonertc-git-4a59f58b' ]
20 verbose mirrorRemote git+https://github.com/alongubkin/phonertc.git git clone https://github.com/alongubkin/phonertc.git
21 verbose correctMkdir /root/.npm/_git-remotes correctMkdir not in flight; initializing
22 verbose setPermissions git+https://github.com/alongubkin/phonertc.git set permissions on /root/.npm/_git-remotes/git-https-github-com-alongubkin-phonertc-git-4a59f58b
23 verbose resolveHead git+https://github.com/alongubkin/phonertc.git original treeish: master
24 info git [ 'rev-list', '-n1', 'master' ]
25 silly resolveHead git+https://github.com/alongubkin/phonertc.git resolved treeish: fed3028ca05d87f04a1b82ebab410f4707c554f5
26 verbose resolveHead git+https://github.com/alongubkin/phonertc.git resolved Git URL: git+https://github.com/alongubkin/phonertc.git#fed3028ca05d87f04a1b82ebab410f4707c554f5
27 silly resolveHead Git working directory: /tmp/npm-2344-d791ca92/git-cache-3208b106/fed3028ca05d87f04a1b82ebab410f4707c554f5
28 info git [ 'clone',
28 info git '/root/.npm/_git-remotes/git-https-github-com-alongubkin-phonertc-git-4a59f58b',
28 info git '/tmp/npm-2344-d791ca92/git-cache-3208b106/fed3028ca05d87f04a1b82ebab410f4707c554f5' ]
29 verbose cloneResolved git+https://github.com/alongubkin/phonertc.git clone Cloning into '/tmp/npm-2344-d791ca92/git-cache-3208b106/fed3028ca05d87f04a1b82ebab410f4707c554f5'...
29 verbose cloneResolved done.
30 info git [ 'checkout', 'fed3028ca05d87f04a1b82ebab410f4707c554f5' ]
31 verbose checkoutTreeish git+https://github.com/alongubkin/phonertc.git checkout Note: checking out 'fed3028ca05d87f04a1b82ebab410f4707c554f5'.
31 verbose checkoutTreeish
31 verbose checkoutTreeish You are in 'detached HEAD' state. You can look around, make experimental
31 verbose checkoutTreeish changes and commit them, and you can discard any commits you make in this
31 verbose checkoutTreeish state without impacting any branches by performing another checkout.
31 verbose checkoutTreeish
31 verbose checkoutTreeish If you want to create a new branch to retain commits you create, you may
31 verbose checkoutTreeish do so (now or later) by using -b with the checkout command again. Example:
31 verbose checkoutTreeish
31 verbose checkoutTreeish git checkout -b
31 verbose checkoutTreeish
31 verbose checkoutTreeish HEAD is now at fed3028... Merge pull request #204 from ShongSu/master
32 info git [ 'submodule', '-q', 'update', '--init', '--recursive' ]
33 verbose updateSubmodules git+https://github.com/alongubkin/phonertc.git submodule update
34 error addLocal Could not install /tmp/npm-2344-d791ca92/git-cache-3208b106/fed3028ca05d87f04a1b82ebab410f4707c554f5
35 silly fetchPackageMetaData Error: EISDIR: illegal operation on a directory, read
35 silly fetchPackageMetaData at Error (native)
35 silly fetchPackageMetaData error for https://github.com/alongubkin/phonertc.git { Error: EISDIR: illegal operation on a directory, read
35 silly fetchPackageMetaData at Error (native) errno: -21, code: 'EISDIR', syscall: 'read' }
36 silly rollbackFailedOptional Starting
37 silly rollbackFailedOptional Finishing
38 silly runTopLevelLifecycles Finishing
39 silly install printInstalled
40 verbose stack Error: EISDIR: illegal operation on a directory, read
40 verbose stack at Error (native)
41 verbose cwd /root/test/node_modules
42 error Linux 4.4.0-79-generic
43 error argv "/usr/bin/nodejs" "/usr/bin/npm" "install" "https://github.com/alongubkin/phonertc.git" "--save"
44 error node v6.11.0
45 error npm v3.10.10
46 error code EISDIR
47 error errno -21
48 error syscall read
49 error eisdir EISDIR: illegal operation on a directory, read
50 error eisdir This is most likely not a problem with npm itself
50 error eisdir and is related to npm not being able to find a package.json in
50 error eisdir a package you are trying to install.
51 verbose exit [ -21, true ]
`