client.alloc-noreset test failure: "memory iteration failed"

I saw this once in PR #4435 but on re-running it did not reproduce. I could not reproduce it locally. It seems rather unlikely to be related to that PR.

https://ci.appveyor.com/project/DynamoRIO/dynamorio/builds/35001136

[00:07:44]         Start  93: code_api|client.alloc-noreset
[00:07:44] 
[00:07:44] 93: Test command: C:\projects\dynamorio\build\build_debug-internal-32\bin32\drrun.exe "-s" "90" "-quiet" "-debug" "-use_dll" "C:/projects/dynamorio/build/build_debug-internal-32/lib32/debug/dynamorio.dll" "-exit0" "-stderr_mask" "0xC" "-msgbox_mask" "0" "-dumpcore_mask" "0x7d" "-staged" "-no_enable_reset" "-no_vm_base_near_app" "-vm_base" "0x120000000" "-vmheap_size" "2G" "-code_api" "-c" "C:/projects/dynamorio/build/build_debug-internal-32/suite/tests/bin/client.alloc-noreset.dll.dll" "--" "C:/projects/dynamorio/build/build_debug-internal-32/suite/tests/bin/client.alloc-noreset.exe"
[00:07:44] 93: Test timeout computed to be: 600
[00:07:44] 93: thank you for testing the client interface
[00:07:44] 93:   testing global memory alloc...success
[00:07:44] 93:   testing nonheap memory alloc...success
[00:07:44] 93:   testing custom memory alloc....success
[00:07:44] 93:   testing custom windows alloc....success
[00:07:44] 93: error: memory iteration failed
[00:07:44] 93:   testing alignment....success
[00:07:44] 93: thread initialization:
[00:07:44] 93:   testing local memory alloc....success
[00:07:44] 93:   testing global memory alloc...success
[00:07:44] 93: code cache:
[00:07:44] 93:   testing local memory alloc....success
[00:07:44] 93:   testing global memory alloc...success
[00:07:44] 93:   testing nonheap memory alloc...success
[00:07:44] 93:   testing raw memory alloc...success
[00:07:44] 93:   testing query pretend-write....success
[00:07:44] 93: wrote to app code page successfully
[00:07:44] 93: all done

[00:17:05]         Start  79: code_api|client.alloc-noreset
[00:17:05] 
[00:17:05] 79: Test command: C:\projects\dynamorio\build\build_debug-internal-64\bin64\drrun.exe "-s" "90" "-quiet" "-debug" "-use_dll" "C:/projects/dynamorio/build/build_debug-internal-64/lib64/debug/dynamorio.dll" "-exit0" "-stderr_mask" "0xC" "-msgbox_mask" "0" "-dumpcore_mask" "0x7d" "-staged" "-no_enable_reset" "-no_vm_base_near_app" "-vm_base" "0x120000000" "-vmheap_size" "2G" "-code_api" "-c" "C:/projects/dynamorio/build/build_debug-internal-64/suite/tests/bin/client.alloc-noreset.dll.dll" "--" "C:/projects/dynamorio/build/build_debug-internal-64/suite/tests/bin/client.alloc-noreset.exe"
[00:17:05] 79: Test timeout computed to be: 600
[00:17:05] 79: thank you for testing the client interface
[00:17:05] 79:   testing global memory alloc...success
[00:17:05] 79:   testing nonheap memory alloc...success
[00:17:05] 79:   testing custom memory alloc....success
[00:17:05] 79:   testing custom windows alloc....success
[00:17:05] 79: error: memory iteration failed
[00:17:05] 79:   testing alignment....success
[00:17:05] 79: thread initialization:
[00:17:05] 79:   testing local memory alloc....success
[00:17:05] 79:   testing global memory alloc...success
[00:17:05] 79: code cache:
[00:17:05] 79:   testing local memory alloc....success
[00:17:05] 79:   testing global memory alloc...success
[00:17:05] 79:   testing nonheap memory alloc...success
[00:17:05] 79:   testing raw memory alloc...success
[00:17:05] 79:   reachability test...success
[00:17:05] 77: LOADED MODULE: COMDLG32.dll
[00:17:05] 79:   testing query pretend-write....success
[00:17:05] 79: wrote to app code page successfully
[00:17:05] 79: all done
[00:17:05] 77: UNLOADED MODULE: COMDLG32.dll
[00:17:05] 77: all done