Can a repository manager or cache enable ember/npm/bower builds even during github.com outage?

How can we insulate our builds against, the pretty rare, github.com outages?

We use maven, frontend-maven-plugin + sonatype-nexus v3.x to create private caches thus insulating our build from outages or modifications made on the main npm repository or via bower dependencies (we cache those too on nexus)

status.github.com reported an outage and we saw our builds begin failing.

By using nexus repos and shrinkwrap we insulated ourselves from the majority of external problems, but not this one.

Let me know if you have any ideas.

Errors

225632 verbose gentlyRm don't care about contents; nuking ./src/frontend/node_modules/.bin/ember
225633 info install ember-cli@2.4.3
225634 info postinstall ember-cli@2.4.3
225635 verbose unlock done using /opt/builds/build-dir/quick-lin-x64-develop/.npm/_locks/ember-cli-387axxxxbbdb3c2.lock for ./src/frontend/node_modules/ember-cli
225636 verbose stack Error: Command failed: git fetch -a origin
225636 verbose stack fatal: remote error:
225636 verbose stack
225636 verbose stack
225636 verbose stack     at ChildProcess.exithandler (child_process.js:744:12)
225636 verbose stack     at ChildProcess.emit (events.js:110:17)
225636 verbose stack     at maybeClose (child_process.js:1008:16)
225636 verbose stack     at Socket.<anonymous> (child_process.js:1176:11)
225636 verbose stack     at Socket.emit (events.js:107:17)
225636 verbose stack     at Pipe.close (net.js:476:12)

[ERROR] npm ERR! argv "src/frontend/node/node" "src/frontend/node/node_modules/npm/bin/npm-cli.js" "install" "--force"
[ERROR] npm ERR! node v0.12.1
[ERROR] npm ERR! npm  v2.14.12
[ERROR] npm ERR! code 128
[ERROR] 
[ERROR] npm ERR! Command failed: git fetch -a origin
[ERROR] npm ERR! fatal: remote error: 
[ERROR] npm ERR!   
[ERROR] npm ERR! 
[ERROR] npm ERR! 
[ERROR] npm ERR! If you need help, you may report this error at:
[ERROR] npm ERR!     <http://ift.tt/1NicLxs;