merge-file --object-id aborts with "cannot reinitialize an already-initialized object directory" in a linked worktree

[LewisADay]

Existing issues matching what you're seeing

• I was not able to find an open or closed issue matching what I'm seeing

Git for Windows version

git version 2.53.0.windows.1
cpu: x86_64
built from commit: a5512bdee37ed7142c233d21e2d347ffc4860ff3
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
libcurl: 8.18.0
OpenSSL: OpenSSL 3.5.5 27 Jan 2026
zlib: 1.3.1
SHA-1: SHA1_DC
SHA-256: SHA256_BLK
default-ref-format: files
default-hash: sha1

Windows version

Windows 11

Windows CPU architecture

x86_64 (64-bit)

Additional Windows version information

Microsoft Windows [Version 10.0.26200.8390]

Options set during installation

Editor Option: VisualStudioCode
Custom Editor Path:
Default Branch Option: main
Path Option: Cmd
SSH Option: OpenSSH
Tortoise Option: false
CURL Option: WinSSL
CRLF Option: CRLFAlways
Bash Terminal Option: MinTTY
Git Pull Behaviour Option: Merge
Use Credential Manager: Enabled
Performance Tweaks FSCache: Enabled
Enable Symlinks: Disabled
Enable FSMonitor: Disabled

Other interesting things

• Three copies of the same OID are used only to minimise the reproducer.
  The bug fires equally with three distinct OIDs which was the discovery vector.

• The failure is independent of blob content, argument order, and the
  --ours/--theirs/--union/--stdout flags.

• Running the very same command from ../bug-repro (the main worktree)
  with the same OID exits 0.

• For reference, the Trace2 output from the failing invocation looks a little something like this:

common-init.c:57  version 2.53.0.windows.1
common-init.c:58  start get.exe merge-file --stdout --object-id <oid> <oid> <oid>
repository.c:237  worktree <path-to-worktree>
git.c:503  cmd_name merge-file (merge-file)
usage.c:346  error cannot reinitialize and already-initialized object directory

• I have replicated this on two machines on version 2.53.0.windows.1, and yet I've been unable to trigger it on one running version 2.47.1.windows.2. For the sake of completeness I include that working installation's system info and install options below

git version 2.47.1.windows.2
cpu: x86_64
built from commit: 36a139e
sizeof-long: 4
sizeof-size_t: 8
shell-path: D:/git-sdk-64/usr/bin/sh
feature: fsmonitor--daemon
libcurl: 8.11.0
OpenSSL: OpenSSL 3.2.3 3 Sep 2024
zlib: 1.3.1
uname: Windows 10.0 26200
compiler info: gnuc: 14.2
libc info: no libc information available
$SHELL (typically, interactive shell):

Editor Option: VisualStudioCode
Custom Editor Path:
Default Branch Option:
Path Option: Cmd
SSH Option: OpenSSH
Tortoise Option: false
CURL Option: OpenSSL
CRLF Option: CRLFAlways
Bash Terminal Option: MinTTY
Git Pull Behavior Option: Merge
Use Credential Manager: Enabled
Performance Tweaks FSCache: Enabled
Enable Symlinks: Disabled
Enable FSMonitor: Disabled

Terminal/shell

PowerShell

Commands that trigger the issue

mkdir bug-repo
cd bug-repo
git init -b main
echo hello > file.txt
git add file.txt
git commit -m init --quiet
git worktree add ../linked --quiet
cd ../linked
$oid=$(git rev-parse HEAD:file.txt)
git merge-file --stdout --object-id "$oid" "$oid" "$oid"

Expected behaviour

Exit code 0, with the blob content written to stdout. (A successful merge)

Actual behaviour

Exit code 3, and output:

BUG: repository.c:171: cannot reinitialize an already-initialized object directory

Repository

No response