Bug report - git rev-list --exclude-first-parent-only [SEC=UNOFFICIAL]

I believe I have found a bug -

My repo has a commit structure like

R2
|\
| F
|/
R1

i.e.
 - there is a merge commit R2 with parents R1 and F
 - the parent of F is R1

I ran "git rev-list --exclude-first-parent-only F ^R2"

it gave the expected result: "F"

I ran "git rev-list --exclude-first-parent-only F R1 ^R2"

I expected the same result, but I got an unexpected result - nothing at all

Suspected cause - I had a look at the code, and it looks like process_parents() in revision.c, when processing uninteresting flags, will skip the 1st parent and mark the 2nd parent as uninteresting if the 1st parent is already SEEN, even with the flag exclude-first-parent-only. I think maybe explicitly selecting R1 on the command line causes it to be marked SEEN before ^R2 is processed, thus resulting in F being marked uninteresting.

[System Info]
git version:
git version 2.54.0.windows.1
cpu: x86_64
built from commit: 2b8a3ab140826ac423c2845ef81d4c6ac4f7bf3c
sizeof-long: 4
sizeof-size_t: 8
shell-path: D:/git-sdk-64-build-installers/usr/bin/sh
rust: disabled
feature: fsmonitor--daemon
gettext: enabled
SHA-1: SHA1_DC
SHA-256: SHA256_BLK
default-ref-format: files
default-hash: sha1

[Enabled Hooks]

Regards, Michael

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