Updating `Mean` with 0 leads to 'No calls to update() have been made...' warning

[dburian]

🐛 Describe the bug

When updating a Mean metric with a zero, calling compute() generates warning that no calls to update() have been made.

from torcheval import metrics
import torch

mean = metrics.Mean()
mean.update(torch.tensor(0.0))

# Generates the warning 'No calls to update() have been made.'
mean.compute()

While the result is obviously correct, the warning is not. It suggests that the code that should be updating the metric is not in fact updating it. Yet the metric is updated as it should be and ergo it should not complain.

Versions

The bug is present in the latest commit to main: a975ef6.

Collecting environment information...
PyTorch version: 2.0.1+cu117
Is debug build: False
CUDA used to build PyTorch: 11.7
ROCM used to build PyTorch: N/A

OS: Manjaro Linux (x86_64)
GCC version: (GCC) 13.2.1 20230801
Clang version: 16.0.6
CMake version: version 3.27.5
Libc version: glibc-2.38

Python version: 3.11.5 (main, Sep  2 2023, 14:16:33) [GCC 13.2.1 20230801] (64-bit runtime)
Python platform: Linux-6.4.16-1-MANJARO-x86_64-with-glibc2.38
Is CUDA available: True
CUDA runtime version: Could not collect
CUDA_MODULE_LOADING set to: LAZY
GPU models and configuration: GPU 0: NVIDIA GeForce GTX 1060 6GB
Nvidia driver version: 535.104.05
cuDNN version: Could not collect
HIP runtime version: N/A
MIOpen runtime version: N/A
Is XNNPACK available: True

CPU:
Architecture:                       x86_64
CPU op-mode(s):                     32-bit, 64-bit
Address sizes:                      43 bits physical, 48 bits virtual
Byte Order:                         Little Endian
CPU(s):                             12
On-line CPU(s) list:                0-11
Vendor ID:                          AuthenticAMD
Model name:                         AMD Ryzen 5 2600X Six-Core Processor
CPU family:                         23
Model:                              8
Thread(s) per core:                 2
Core(s) per socket:                 6
Socket(s):                          1
Stepping:                           2
BogoMIPS:                           7201.75
Flags:                              fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate ssbd ibpb vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 clzero irperf xsaveerptr arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov succor smca sev sev_es
Virtualization:                     AMD-V
L1d cache:                          192 KiB (6 instances)
L1i cache:                          384 KiB (6 instances)
L2 cache:                           3 MiB (6 instances)
L3 cache:                           16 MiB (2 instances)
NUMA node(s):                       1
NUMA node0 CPU(s):                  0-11
Vulnerability Gather data sampling: Not affected
Vulnerability Itlb multihit:        Not affected
Vulnerability L1tf:                 Not affected
Vulnerability Mds:                  Not affected
Vulnerability Meltdown:             Not affected
Vulnerability Mmio stale data:      Not affected
Vulnerability Retbleed:             Mitigation; untrained return thunk; SMT vulnerable
Vulnerability Spec rstack overflow: Mitigation; safe RET
Vulnerability Spec store bypass:    Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:           Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:           Mitigation; Retpolines, IBPB conditional, STIBP disabled, RSB filling, PBRSB-eIBRS Not affected
Vulnerability Srbds:                Not affected
Vulnerability Tsx async abort:      Not affected

Versions of relevant libraries:
[pip3] mypy-extensions==1.0.0
[pip3] numpy==1.24.3
[pip3] torch==2.0.1
[pip3] torcheval==0.0.7
[pip3] torchvision==0.15.2
[pip3] triton==2.0.0
[conda] Could not collect

[bobakfb]

Thanks @dburian , addressing