[Setup] Handle env variable DEBUG = ""

Summary:

This was not handled and run into `int("")` failing.

Test Plan:

Locally tested installing with `export DEBUG=""`.

Reviewers:

Subscribers:

Tasks:
Resolves #8311

Tags:

Author: digantdesai

setup.py

@@ -169,7 +169,7 @@ def write_to_python_file(cls, path: str) -> None:
 # set to a non-empty value, the build type is Debug. Otherwise, the build type
 # is Release.
 def get_build_type(is_debug=None) -> str:
-    debug = int(os.environ.get("DEBUG", 0)) if is_debug is None else is_debug
+    debug = int(os.environ.get("DEBUG", 0) or 0) if is_debug is None else is_debug
     cfg = "Debug" if debug else "Release"
     return cfg
 
@@ -239,11 +239,11 @@ def src_path(self, installer: "InstallerBuildExt") -> Path:
         srcs = tuple(cmake_cache_dir.glob(self.src))
         if len(srcs) != 1:
             raise ValueError(
-                f"""Expected exactly one file matching '{self.src}'; found {repr(srcs)}. 
+                f"""Expected exactly one file matching '{self.src}'; found {repr(srcs)}.
 
 If that file is a CMake-built extension module file, and we are installing in editable mode, please disable the corresponding build option since it's not supported yet.
 
-Try: 
+Try:
 
 EXECUTORCH_BUILD_FLATC=OFF EXECUTORCH_BUILD_KERNELS_CUSTOM_AOT=OFF pip install -e .
 """