knoxshell buildTrustStore doesn't work on a url without a port

./bin/knoxshell.sh buildTrustStore https://knox_host
Opening connection to knoxhost:-1...
org.apache.knox.gateway.shell.KnoxShellException: Error while building trust store
	at org.apache.knox.gateway.shell.KnoxSh$KnoxBuildTrustStore.execute(KnoxSh.java:194)
	at org.apache.knox.gateway.shell.KnoxSh.run(KnoxSh.java:85)
	at org.apache.knox.gateway.shell.KnoxSh.main(KnoxSh.java:392)
Caused by: java.lang.IllegalArgumentException: port out of range:-1
	at java.net.InetSocketAddress.checkPort(InetSocketAddress.java:143)
	at java.net.InetSocketAddress.<init>(InetSocketAddress.java:224)
	at sun.security.ssl.SSLSocketImpl.<init>(SSLSocketImpl.java:423)
	at sun.security.ssl.SSLSocketFactoryImpl.createSocket(SSLSocketFactoryImpl.java:88)
	at org.apache.knox.gateway.shell.KnoxSh$KnoxBuildTrustStore.fetchPublicCertsFromGatewayServer(KnoxSh.java:209)
	at org.apache.knox.gateway.shell.KnoxSh$KnoxBuildTrustStore.execute(KnoxSh.java:186)
	... 2 more