build.bash: fail early if the go binary does not exist

This used to fail in an ugly way:

  $ ./build.bash
  ./build.bash: line 13: go: command not found
  ./build.bash: line 15: [: too many arguments
  ./build.bash: line 20: go: command not found

1 files changed, 3 insertions, 0 deletions

diff --git a/build.bash b/build.bash
index 3a3684e..c7731ca 100755
--- a/build.bash
+++ b/build.bash
@@ -9,6 +9,9 @@ GITVERSION=$(git describe --tags --dirty)
 # go-fuse version according to git
 GITVERSIONFUSE=$(cd $GOPATH/src/github.com/hanwen/go-fuse && git rev-parse --short HEAD)
 
+# Make sure we have the go binary
+go version > /dev/null
+
 # go version go1.5.1 linux/amd64
 V=$(go version | cut -d" " -f3 | cut -c3-5)