[Autoroller] github_deps_repo_manager runhooks needs depot_tools env

Change-Id: I9142f9a30923977fc572f146bb3004899cf26f59
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/179140
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
diff --git a/autoroll/go/repo_manager/github_deps_repo_manager.go b/autoroll/go/repo_manager/github_deps_repo_manager.go
index 5db4ef7..b005195 100644
--- a/autoroll/go/repo_manager/github_deps_repo_manager.go
+++ b/autoroll/go/repo_manager/github_deps_repo_manager.go
@@ -6,7 +6,6 @@
 	"net/http"
 	"os"
 	"path"
-	"path/filepath"
 	"strings"
 
 	"go.skia.org/infra/autoroll/go/codereview"
@@ -88,7 +87,12 @@
 				return fmt.Errorf("Could not create and sync %s: %s", rm.parentDir, err)
 			}
 			// Run gclient hooks to bring in any required binaries.
-			if _, err := exec.RunCwd(ctx, rm.parentDir, filepath.Join(rm.depotTools, "gclient"), "runhooks"); err != nil {
+			if _, err := exec.RunCommand(ctx, &exec.Command{
+				Dir:  rm.parentDir,
+				Env:  rm.depotToolsEnv,
+				Name: rm.gclient,
+				Args: []string{"runhooks"},
+			}); err != nil {
 				return fmt.Errorf("Error when running gclient runhooks on %s: %s", rm.parentDir, err)
 			}
 		} else {