No leap second on 2018-06-30.

Per IERS Bulletin C55 (2018-01-09), no leap second on 2018-06-30.
https://datacenter.iers.org/eop/-/somos/5Rgv/getTX/16/bulletinc-055.txt

* leap-seconds.list: Update file from NIST, retrieved from
<ftp://ftp.nist.gov/pub/time/leap-seconds.list>.

leap-seconds.list

@@ -61,7 +61,12 @@
 #	or
 #		Terry Quinn, "The BIPM and the Accurate Measurement
 #		of Time," Proc. of the IEEE, Vol. 79, pp. 894-905,
-#		July, 1991.
+#		July, 1991. <http://dx.doi.org/10.1109/5.84965>
+#		reprinted in: 
+#		   Christine Hackman and Donald B Sullivan (eds.)
+#		   Time and Frequency Measurement
+#		   American Association of Physics Teachers (1996)
+#		   <http://tf.nist.gov/general/pdf/1168.pdf>, pp. 75-86
 #
 #	4. The decision to insert a leap second into UTC is currently
 #	the responsibility of the International Earth Rotation and
@@ -199,10 +204,10 @@
 #	current -- the update time stamp, the data and the name of the file
 #	will not change.
 #
-#	Updated through IERS Bulletin C54
-#	File expires on:  28 June 2018
+#	Updated through IERS Bulletin C55
+#	File expires on:  28 December 2018
 #
-#@	3739132800
+#@	3754944000
 #
 2272060800	10	# 1 Jan 1972
 2287785600	11	# 1 Jul 1972
@@ -247,4 +252,4 @@
 #	the hash line is also ignored in the
 #	computation.
 #
-#h	5101445a 69948b51 9153e2b 2086e3d8 d54561a3
+#h	44dcf58c e28d25aa b36612c8 f3d3e8b5 a8fdf478