enable long paths and do not materialize symlinks on Linux

.pfnci/wheel-windows/build.ps1

@@ -11,6 +11,7 @@ $ErrorActionPreference = "Stop"
 . "$PSScriptRoot\_flexci.ps1"
 
 PrioritizeFlexCIDaemon
+EnableLongPaths
 
 function UninstallCuDNN($cuda_path) {
     echo "Uninstalling cuDNN installation from ${cuda_path}"
@@ -55,6 +56,8 @@ echo ">> Using Branch: $branch"
 
 # Clone CuPy and checkout the target branch
 RunOrDie git clone --recursive --branch $branch --depth 1 https://github.com/cupy/cupy.git cupy
+RunOrDie git -C cupy config core.symlinks true
+RunOrDie git -C cupy reset --hard
 
 # Get Cython version from configuration.
 $cython_version = @(python -c "import dist_config; print(dist_config.CYTHON_VERSION)")

dist.py

@@ -386,7 +386,7 @@ def build_linux(
 
             # Copy source tree to working directory.
             log('Copying source tree from: {}'.format(source))
-            shutil.copytree(source, '{}/cupy'.format(workdir))
+            shutil.copytree(source, '{}/cupy'.format(workdir), symlinks=True)
 
             # Add long description file.
             with open('{}/description.rst'.format(workdir), 'w') as f:
@@ -541,7 +541,7 @@ def build_windows(
         try:
             log('Using working directory: {}'.format(workdir))
 
-            # Copy source tree and NCCL to working directory.
+            # Copy source tree to working directory.
             log('Copying source tree from: {}'.format(source))
             shutil.copytree(source, '{}/cupy'.format(workdir))