travis: reset tree before the generate check
MODIFY
.travis/script.d/check-generate.sh
.travis/script.d/check-generate.sh
#!/bin/bash
+# Reset the tree to the current commit to handle
+# any writes during the build.
+git reset --hard
+
go generate gonum.org/v1/gonum/blas
go generate gonum.org/v1/gonum/blas/gonum
go generate gonum.org/v1/gonum/unit

travis: reset tree before the generate check