So node is failing on hydra[0] and building it locally brought equal results. As I'm not familiar with node at all I don't know if my inclusion of node is not necessary for mastodon, so I will give it a try without node.
I know many things are failing right now, but I do not have enough knowledge of node to understand why the test suite fails suddenly. Maybe some dependency needed only for the test which is failing before node? This is the local node output after the build phase succeeded: phase `build' succeeded after 350.4 seconds starting phase `check' make -C out BUILDTYPE=Release V=1 make[1]: Entering directory '/tmp/guix-build-node-6.0.0.drv-0/node-v6.0.0/out' make[1]: Nothing to be done for 'all'. make[1]: Leaving directory '/tmp/guix-build-node-6.0.0.drv-0/node-v6.0.0/out' ln -fs out/Release/node node Running main() from gtest_main.cc [==========] Running 1 test from 1 test case. [----------] Global test environment set-up. [----------] 1 test from UtilTest [ RUN ] UtilTest.ListHead [ OK ] UtilTest.ListHead (0 ms) [----------] 1 test from UtilTest (0 ms total) [----------] Global test environment tear-down [==========] 1 test from 1 test case ran. (0 ms total) [ PASSED ] 1 test. /gnu/store/vcx1n5nj4gr52xx5m6gvi7zrwngy06s3-python-2.7.11/bin/python tools/test.py --mode=release message parallel sequential -J === release test-tls-alpn-server-client === Path: parallel/test-tls-alpn-server-client assert.js:90 throw new assert.AssertionError({ ^ AssertionError: 'first-priority-unsupported' === false at checkResults (/tmp/guix-build-node-6.0.0.drv-0/node-v6.0.0/test/parallel/test-tls-alpn-server-client.js:32:10) at /tmp/guix-build-node-6.0.0.drv-0/node-v6.0.0/test/parallel/test-tls-alpn-server-client.js:101:5 at TLSSocket.<anonymous> (/tmp/guix-build-node-6.0.0.drv-0/node-v6.0.0/test/parallel/test-tls-alpn-server-client.js:66:9) at TLSSocket.g (events.js:286:16) at emitNone (events.js:86:13) at TLSSocket.emit (events.js:185:7) at TLSSocket.<anonymous> (_tls_wrap.js:1072:16) at emitNone (events.js:86:13) at TLSSocket.emit (events.js:185:7) at TLSSocket._finishInit (_tls_wrap.js:580:8) Command: out/Release/node /tmp/guix-build-node-6.0.0.drv-0/node-v6.0.0/test/parallel/test-tls-alpn-server-client.js [01:28|% 100|+ 1077|- 1]: Done make: *** [Makefile:118: test] Error 1 phase `check' failed after 89.5 seconds builder for `/gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv' failed with exit code 1 @ build-failed /gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv - 1 builder for `/gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv' failed with exit code 1 guix build: error: build failed: build of `/gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv' failed Cannot open display "default display" derivation '/gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv' offloaded to '192.168.1.198' failed with exit code 1 @ build-failed /gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv - 1 builder for `/gnu/store/x4x6j7d4sgf888iijkf9brjb38b94h8z-node-6.0.0.drv' failed with exit code 100 cannot build derivation `/gnu/store/11sh5qwmp7a0pbb8hccmlymhc6l3i588-mastodon-0.7.drv': 1 dependencies couldn't be built guix build: error: build failed: build of `/gnu/store/11sh5qwmp7a0pbb8hccmlymhc6l3i588-mastodon-0.7.drv' failed [0]: http://hydra.gnu.org/job/gnu/core-updates/node-6.0.0.x86_64-linux