Skip wheel patching with empty patches

Fixes #2263

Author: keith

python/private/pypi/patch_whl.bzl

@@ -60,6 +60,9 @@ def patch_whl(rctx, *, python_interpreter, whl_path, patches, **kwargs):
     if not rctx.delete(whl_file_zip):
         fail("Failed to remove the symlink after extracting")
 
+    if not patches:
+        fail("Trying to patch wheel without any patches")
+
     for patch_file, patch_strip in patches.items():
         rctx.patch(patch_file, strip = patch_strip)
 

python/private/pypi/whl_library.bzl

@@ -266,15 +266,16 @@ def _whl_library_impl(rctx):
             if whl_path.basename in patch_dst.whls:
                 patches[patch_file] = patch_dst.patch_strip
 
-        whl_path = patch_whl(
-            rctx,
-            op = "whl_library.PatchWhl({}, {})".format(rctx.attr.name, rctx.attr.requirement),
-            python_interpreter = python_interpreter,
-            whl_path = whl_path,
-            patches = patches,
-            quiet = rctx.attr.quiet,
-            timeout = rctx.attr.timeout,
-        )
+        if patches:
+            whl_path = patch_whl(
+                rctx,
+                op = "whl_library.PatchWhl({}, {})".format(rctx.attr.name, rctx.attr.requirement),
+                python_interpreter = python_interpreter,
+                whl_path = whl_path,
+                patches = patches,
+                quiet = rctx.attr.quiet,
+                timeout = rctx.attr.timeout,
+            )
 
     target_platforms = rctx.attr.experimental_target_platforms
     if target_platforms: