qt5 windows qtwebassembly builds timeout after 15 min

agent:2020/02/12 03:35:23 build.go:484: Executing instruction 66 of 66 - ExecuteCommand
agent:2020/02/12 03:35:23 build.go:550: [\Users\qt\work\qt\qt5\configure.bat -opensource -confirm-license -verbose -prefix c:\Users\qt\work\install -release -nomake examples -nomake tests -no-feature-thread -static -no-dbus -no-headersclean -no-ssl -no-warnings-are-errors -no-pch -platform win32-g++ -xplatform wasm-emscripten -qt-zlib]  900
[...]
agent:2020/02/12 03:50:23 build.go:138: Virtual Memory Total: 9663135744, Free:0, UsedPercent:40.000000%
agent:2020/02/12 03:50:23 build.go:269: Killed process: Maximum step duration reached (timeout: 900 seconds)
agent:2020/02/12 03:50:23 build.go:471: Executing scheduled instruction 1 of 1 - Upload all core dumps if there are some
agent:2020/02/12 03:50:24 build.go:384: Skip uploading core files because CORE_FILES_PATH is not set in the environment
agent:2020/02/12 03:50:24 build.go:473: 
agent:2020/02/12 03:50:24 agent.go:272: Build failed
agent:2020/02/12 03:50:24 agent.go:200: ERROR building: Timeout after 15m0s: Maximum duration reached
agent:2020/02/12 03:50:24 build.go:223: Error reading from stdout/err: Timeout after 15m0s: Maximum duration reached