Transient failure of lazy_loader_spec.js

Running Karma tests locally, I occasionally have this failure:

LazyLoader behavior should copy value from data-src to src for img 1 FAILED
	Expected 'data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==' to be 'https://www.gravatar.com/avatar/9890e747cab638f819123d426b0b28ea?s=46&d=identicon'.

	actual expected

	data:imagehttps://www.gravatar.com/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==avatar/9890e747cab638f819123d426b0b28ea?s=46&d=identicon

	    at webpack://.../spec/javascripts/lazy_loader_spec.js:25 <- spec/javascripts/test_bundle.js:564309:41
	Expected 0 to be greater than 0.
	    at webpack://.../spec/javascripts/lazy_loader_spec.js:26 <- spec/javascripts/test_bundle.js:564310:74

I wasn't able to reproduce and it goes away when retrying.