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sdk/lib/_internal/pub/lib/src/command/build.dart

Index: sdk/lib/_internal/pub/lib/src/command/build.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command/build.dart b/sdk/lib/_internal/pub/lib/src/command/build.dart
index 22b95b8b9d88879ffc982db480a12e26af3c84b4..04d8ea61d13e60496bafb08455636a0dd922950c 100644
--- a/sdk/lib/_internal/pub/lib/src/command/build.dart
+++ b/sdk/lib/_internal/pub/lib/src/command/build.dart
@@ -70,6 +70,10 @@ class BuildCommand extends PubCommand {
         // Figure out the output directory for the asset, which is the same
         // as the path pub serve would use to serve it.
         var relativeUrl = barback.idtoUrlPath(entrypoint.root.name, asset.id);
+
+        // Remove the leading "/".
+        relativeUrl = relativeUrl.substring(1);
+
         var relativePath = path.fromUri(new Uri(path: relativeUrl));
         var destPath = path.join(target, relativePath);