[CI] Fix b200 flashinfer installation (#11915)

Signed-off-by: Shangming Cai <csmthu@gmail.com>

scripts/ci/ci_install_dependency.sh

@@ -27,6 +27,9 @@ if [ "$IS_BLACKWELL" = "1" ]; then
 
     # Clean up existing installations
     $PIP_CMD uninstall -y flashinfer_python sgl-kernel sglang vllm $PIP_INSTALL_SUFFIX || true
+
+    # Install the main package
+    $PIP_CMD install -e "python[dev]" --extra-index-url https://download.pytorch.org/whl/${CU_VERSION} $PIP_INSTALL_SUFFIX --force-reinstall
 else
     # In normal cases, we use uv, which is much faster than pip.
     pip install --upgrade pip
@@ -38,16 +41,16 @@ else
 
     # Clean up existing installations
     $PIP_CMD uninstall flashinfer_python sgl-kernel sglang vllm || true
-fi
 
-# Install the main package without deps
-$PIP_CMD install -e "python[dev]" --no-deps $PIP_INSTALL_SUFFIX --force-reinstall
+    # Install the main package without deps
+    $PIP_CMD install -e "python[dev]" --no-deps $PIP_INSTALL_SUFFIX --force-reinstall
 
-# Install flashinfer-python 0.4.0 dependency that requires prerelease (This should be removed when flashinfer fixes this issue)
-$PIP_CMD install flashinfer-python==0.4.0 --prerelease=allow $PIP_INSTALL_SUFFIX
+    # Install flashinfer-python 0.4.0 dependency that requires prerelease (This should be removed when flashinfer fixes this issue)
+    $PIP_CMD install flashinfer-python==0.4.0 --prerelease=allow $PIP_INSTALL_SUFFIX
 
-# Install the main package
-$PIP_CMD install -e "python[dev]" --extra-index-url https://download.pytorch.org/whl/${CU_VERSION} $PIP_INSTALL_SUFFIX --upgrade
+    # Install the main package
+    $PIP_CMD install -e "python[dev]" --extra-index-url https://download.pytorch.org/whl/${CU_VERSION} $PIP_INSTALL_SUFFIX --upgrade
+fi
 
 # Install router for pd-disagg test
 SGLANG_ROUTER_BUILD_NO_RUST=1 $PIP_CMD install -e "sgl-router" $PIP_INSTALL_SUFFIX