JRuby head fails to build #409

Job	Run time
ruby-versions / Generate Ruby versions	4s
build (2.5, 0.1.7, /tmp/local)	1m 15s
build (2.5, 0.1.7)	35s
build (2.5, 0.2.5, /tmp/local)	1m 11s
build (2.5, 0.2.5)	34s
build (2.6, 0.1.7, /tmp/local)	58s
build (2.6, 0.1.7)	39s
build (2.6, 0.2.5, /tmp/local)	58s
build (2.6, 0.2.5)	1m 12s
build (2.7, 0.1.7, /tmp/local)	58s
build (2.7, 0.1.7)	1m 10s
build (2.7, 0.2.5, /tmp/local)	58s
build (2.7, 0.2.5)	38s
build (3.0, 0.1.7, /tmp/local)	50s
build (3.0, 0.1.7)	21s
build (3.0, 0.2.5, /tmp/local)	31s
build (3.0, 0.2.5)	21s
build (3.1, 0.1.7, /tmp/local)	43s
build (3.1, 0.1.7)	20s
build (3.1, 0.2.5, /tmp/local)	27s
build (3.1, 0.2.5)	21s
build (3.2, 0.1.7, /tmp/local)	39s
build (3.2, 0.1.7)	29s
build (3.2, 0.2.5, /tmp/local)	42s
build (3.2, 0.2.5)	21s
build (3.3, 0.1.7, /tmp/local)	42s
build (3.3, 0.1.7)	41s
build (3.3, 0.2.5, /tmp/local)	55s
build (3.3, 0.2.5)	35s
build (3.4, 0.1.7, /tmp/local)	27s
build (3.4, 0.1.7)	23s
build (3.4, 0.2.5, /tmp/local)	55s
build (3.4, 0.2.5)	52s
build (head, 0.1.7, /tmp/local)	27s
build (head, 0.1.7)	22s
build (head, 0.2.5, /tmp/local)	25s
build (head, 0.2.5)	31s
	24m 30s

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