When using glide tree to print dependency tree , I found a error.

| |-- github.com/go-sql-driver/mysql (/home/gubei/gocode/src/github.com/xiaohuanggua/virgin/vendor/github.com/go-sql-driver/mysql)
| | |-- appengine/cloudsql ()
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x20 pc=0x4e2233]

goroutine 1 [running]:
panic(0x945080, 0xc82000e170)
/usr/local/Cellar/go/1.6/libexec/src/runtime/panic.go:464 +0x3e6
github.com/Masterminds/glide/dependency.srcDir(0x0, 0x0, 0xc81ffea1e0)
/Users/mfarina/Code/go/src/github.com/Masterminds/glide/dependency/resolver.go:927 +0x33
github.com/Masterminds/glide/dependency.IsSrcDir(0x0, 0x0, 0xc81ffea1e0)
/Users/mfarina/Code/go/src/github.com/Masterminds/glide/dependency/resolver.go:923 +0x2b
github.com/Masterminds/glide/tree.walkDeps.func1(0x0, 0x0, 0x0, 0x0, 0x7fa5ea9a1608, 0xc8202bc3f0, 0x0, 0x0)
/Users/mfarina/Code/go/src/github.com/Masterminds/glide/tree/tree.go:48 +0x92
path/filepath.Walk(0x0, 0x0, 0xc8201ccac8, 0x0, 0x0)
/usr/local/Cellar/go/1.6/libexec/src/path/filepath/path.go:394 +0x

my os system is fedora linux .

thank you for helping.