This is a funny bug. I discovered it when deploying the new upcoming WPE EWS queue (see bug 250706) All the bots were failing to build without patch (step: compile-webkit-without-change) Example: https://ews-build.webkit.org/#/builders/86/builds/37/steps/31/logs/stdio This is because this layout-test EWS bots do the following (very summarized). 1) Download and un-compress the built-product from the build-only EWS bot 2) Run layout tests 3) if there are unexpected failures, unapply patch and build WebKit without patch. And the issue here is that the build-products that the build-only EWS bots were generating included some stamp files like: ./Tools/cog-prefix/src/cog-stamp/cog-gitclone-lastrun.txt ./Tools/cog-prefix/src/cog-stamp/cog-patch ./Tools/cog-prefix/src/cog-stamp/cog-build ./Tools/cog-prefix/src/cog-stamp/cog-done ./Tools/cog-prefix/src/cog-stamp/cog-configure ./Tools/cog-prefix/src/cog-stamp/cog-gitinfo.txt ./Tools/cog-prefix/src/cog-stamp/cog-install ./Tools/cog-prefix/src/cog-stamp/cog-mkdir ./Tools/cog-prefix/src/cog-stamp/cog-download So this caused that when CMake tried to re-build without patch it skipped the step 'cog gitclone' and since the bots were recently deployed it didn't had a cog clone from a previous run. This can be easily reproduced as follows: works: rm -fr Tools/wpe/cog WebKitBuild/WPE/Release/ Tools/Scripts/build-webkit --wpe --release fails: rm -fr Tools/wpe/cog WebKitBuild/WPE/Release/ python3 Tools/CISupport/download-built-product --release https://s3-us-west-2.amazonaws.com/ews-archives.webkit.org/wpe-x86_64-release/8c3872d5.zip python3 Tools/CISupport/built-product-archive --platform=wpe --release extract Tools/Scripts/build-webkit --wpe --release [6980/7234] Performing download step (git clone) for 'cog' -- Avoiding repeated git clone, stamp file is up to date: '/app/webkit/WebKitBuild/Release/Tools/cog-prefix/src/cog-stamp/cog-gitclone-lastrun.txt' [6981/7234] Performing update step for 'cog' FAILED: Tools/cog-prefix/src/cog-stamp/cog-update /app/webkit/WebKitBuild/Release/Tools/cog-prefix/src/cog-stamp/cog-update cd /app/webkit/Tools/wpe/cog && /usr/bin/cmake -P /app/webkit/WebKitBuild/Release/Tools/cog-prefix/tmp/cog-gitupdate.cmake CMake Error at /app/webkit/WebKitBuild/Release/Tools/cog-prefix/tmp/cog-gitupdate.cmake:25 (message): Failed to get the hash for HEAD: fatal: not a git repository: '.git'