I've tried the /backport bot command on an openjdk/jdk commit. When I've tried it, a dependency bug hasn't been integrated yet. However, when I tried it again *with* the dependency integrated it still reported conflicts in files, which didn't happen when I did the commands manually.

jdk head commit with the comment history:
https://github.com/openjdk/jdk/commit/2963c9e6778b95f5c0fc4298064a21d1e8f31b91

When trying locally, it applied clean:

$ git fetch jdk-jdk --no-tags 2963c9e6778b95f5c0fc4298064a21d1e8f31b91
remote: Enumerating objects: 279995, done.
remote: Counting objects: 100% (101004/101004), done.
remote: Total 279995 (delta 101004), reused 101004 (delta 101004), pack-reused 178991
Receiving objects: 100% (279995/279995), 151.53 MiB | 9.36 MiB/s, done.
Resolving deltas: 100% (210212/210212), completed with 20912 local objects.
From https://github.com/openjdk/jdk
 * branch 2963c9e6778b95f5c0fc4298064a21d1e8f31b91 -> FETCH_HEAD
[sgehwolf@t580-laptop jdk11u-dev]$ git cherry-pick 2963c9e6778b95f5c0fc4298064a21d1e8f31b91
Auto-merging src/jdk.management/macosx/native/libmanagement_ext/UnixOperatingSystem.c
Auto-merging src/jdk.management/aix/native/libmanagement_ext/UnixOperatingSystem.c
warning: inexact rename detection was skipped due to too many files.
warning: you may want to set your merge.renamelimit variable to at least 11565 and retry the command.
[jdk-8268103-osbean-native-double-fix 2bfece19597] 8268103: JNI functions incorrectly return a double after JDK-8265836
 Author: Severin Gehwolf <sgehwolf@openjdk.org>
 Date: Wed Jun 2 12:18:30 2021 +0000
 2 files changed, 2 insertions(+), 2 deletions(-)


So IMO, the '/backport jdk11u-dev' command in the following comment should have worked:
https://github.com/openjdk/jdk/commit/2963c9e6778b95f5c0fc4298064a21d1e8f31b91#commitcomment-52122825