panic on FileSystemList.Get

[bananabrick]

goroutine 83 [running]:
github.com/elastic/gosigar.(*FileSystemList).Get.func1({0xc0019b8ab0, 0xc000ae9000})
	github.com/elastic/gosigar/external/com_github_elastic_gosigar/sigar_linux_common.go:113 +0x1b0
github.com/elastic/gosigar.readFile({0x4e8860e, 0x200000003}, 0xc000ac7440)
	github.com/elastic/gosigar/external/com_github_elastic_gosigar/sigar_linux_common.go:386 +0x208
github.com/elastic/gosigar.(*FileSystemList).Get(0xc000ac7508)
	github.com/elastic/gosigar/external/com_github_elastic_gosigar/sigar_linux_common.go:106 +0x8f
github.com/cockroachdb/cockroach/pkg/storage.getFileSystemProperties({0x6355138, 0xc000828e40}, {0xc00095f2f0, 0x21})
	github.com/cockroachdb/cockroach/pkg/storage/store_properties.go:60 +0x1d4
github.com/cockroachdb/cockroach/pkg/storage.computeStoreProperties({0x6355138, 0xc000828e40}, {0xc00095f2f0, 0x3d}, 0x47, 0x59)

If an entry in the mount table file doesn't have the options defined, then FileSystemList.Get can panic as shown.

[dkossako]

This issue is related to present docker volumes in OS. When docker is turned off (service docker stop) then cockroach starts fine.