Skip logging the warning for uncrypt_status for devices w/o /cache

This warning may cause confusion for users.

Bug: 36590598
Test: Warning line no longer shows for sailfish.
Change-Id: I277c87a50a72fdb499be790ee25b97f815d980be
(cherry picked from commit bcb5b18630f518835a0768535b43ccfe91683fc9)
diff --git a/install.cpp b/install.cpp
index a256d9b..7cef44a 100644
--- a/install.cpp
+++ b/install.cpp
@@ -546,17 +546,21 @@
     std::chrono::duration<double> duration = std::chrono::system_clock::now() - start;
     int time_total = static_cast<int>(duration.count());
 
-    if (ensure_path_mounted(UNCRYPT_STATUS) != 0) {
+    bool has_cache = volume_for_path("/cache") != nullptr;
+    // Skip logging the uncrypt_status on devices without /cache.
+    if (has_cache) {
+      if (ensure_path_mounted(UNCRYPT_STATUS) != 0) {
         LOG(WARNING) << "Can't mount " << UNCRYPT_STATUS;
-    } else {
+      } else {
         std::string uncrypt_status;
         if (!android::base::ReadFileToString(UNCRYPT_STATUS, &uncrypt_status)) {
-            PLOG(WARNING) << "failed to read uncrypt status";
+          PLOG(WARNING) << "failed to read uncrypt status";
         } else if (!android::base::StartsWith(uncrypt_status, "uncrypt_")) {
-            LOG(WARNING) << "corrupted uncrypt_status: " << uncrypt_status;
+          LOG(WARNING) << "corrupted uncrypt_status: " << uncrypt_status;
         } else {
-            log_buffer.push_back(android::base::Trim(uncrypt_status));
+          log_buffer.push_back(android::base::Trim(uncrypt_status));
         }
+      }
     }
 
     // The first two lines need to be the package name and install result.