print error message, not {e}

BUG=None
TEST=CQ!

Change-Id: I0986fdfe6c37e3a1e70a08c13e88506158232f75
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/5304252
Commit-Queue: Derek Beckett <dbeckett@chromium.org>
Tested-by: Derek Beckett <dbeckett@chromium.org>
Reviewed-by: Parker Holloway <jparkerh@google.com>
diff --git a/src/chromiumos/test/python/src/docker_libs/cli/build-dockerimages.py b/src/chromiumos/test/python/src/docker_libs/cli/build-dockerimages.py
index f6c020a..5199663 100755
--- a/src/chromiumos/test/python/src/docker_libs/cli/build-dockerimages.py
+++ b/src/chromiumos/test/python/src/docker_libs/cli/build-dockerimages.py
@@ -296,7 +296,7 @@
             else:
                 print(
                     f"Build failed, will retry in {args.retry_wait} "
-                    "seconds:\n{e}"
+                    f"seconds:\n{e}"
                 )
                 time.sleep(args.retry_wait)
         retries -= 1