When I gomote push from a tree that has a VERSION file, the VERSION file does not end up on the gomote.

% gomote push $vm
2022/12/03 15:41:27 installing go1.4
2022/12/03 15:41:41 Remote doesn't have "src/go/internal/gcimporter/exportdata.go"
2022/12/03 15:41:41 Remote doesn't have "src/runtime/testdata/testprog/sleep.go"
2022/12/03 15:41:41 Remote doesn't have "src/runtime/testdata/testprog/syscalls_none.go"
2022/12/03 15:41:41 Remote doesn't have "src/runtime/trace/trace_stack_test.go"
2022/12/03 15:41:41 Remote doesn't have "src/syscall/exec_aix_test.go"
2022/12/03 15:41:41 Remote doesn't have 12036 files (only showed 5).
2022/12/03 15:41:41 Remote lacks a VERSION file; sending a fake one
2022/12/03 15:41:48 Uploading 12037 new/changed files; 79017606 byte .tar.gz
...

From the messages, you'd think that the fake VERSION is sent before the upload, meaning the upload should overwrite it. But 'gomote ssh' to the VM and printing the VERSION file shows the devel gomote.XXXXX content and not the one I have locally (which says go1.99).

Maybe there's an ordering issue, I thought, so I ran gomote push again. That definitely sends the VERSION file:

% gomote push $vm
...
2022/12/03 15:43:39 Remote's VERSION digest is "06e08a5ba98f3aa9496d990cc86f4a96fde9687d"; want "f51724a3e09407fd330585a259fd89c12e40e159"
...
% echo -n 'devel gomote.XXXXX' | openssl sha1
06e08a5ba98f3aa9496d990cc86f4a96fde9687d
% echo go1.99 | openssl sha1
f51724a3e09407fd330585a259fd89c12e40e159
% 

And yet, it remains unchanged on the server (confirmed with 'type VERSION' in ssh). It is as though the buildlet discards uploaded VERSION files. This is on the windows-amd64-2016 gomote, in case the specific buildlet matters.

I have been working on reproducible builds, which are only possible in non-devel trees, so I need to send a VERSION file. I have resorted to running a batch file that echoes the right content into the VERSION file before running the command I want to run. So I'm not blocked, but it was a surprising thing to debug in the first place.