imageloader: Fix to error logging for --unmount_all.

BUG=chromium:760007
BUG=chromium:773924
TEST=test_that -b amd64-generic <ip:port> platform_ImageLoaderServer

Change-Id: Idf22cd6f52c00ce93a511c3ba54e9b9ea190e682
Reviewed-on: https://chromium-review.googlesource.com/713637
Commit-Ready: Allen Webb <allenwebb@google.com>
Tested-by: Greg Kerr <kerrnel@chromium.org>
Reviewed-by: Greg Kerr <kerrnel@chromium.org>
(cherry picked from commit 1e51d8b63530b571c20edc37c0e336637d1f9e00)
Reviewed-on: https://chromium-review.googlesource.com/718992
Commit-Queue: Greg Kerr <kerrnel@chromium.org>
Trybot-Ready: Greg Kerr <kerrnel@chromium.org>
diff --git a/imageloader_main.cc b/imageloader_main.cc
index bd9f994..eea3ac3 100644
--- a/imageloader_main.cc
+++ b/imageloader_main.cc
@@ -100,8 +100,11 @@
         std::cout << path.value() << "\n";
       }
     }
-    LOG(ERROR) << "--unmount_all failed!";
-    return success ? 0 : 1;
+    if (!success) {
+      LOG(ERROR) << "--unmount_all failed!";
+      return 1;
+    }
+    return 0;
   }
 
   if (FLAGS_unmount) {