[llvm] [LIT] Fix env without subcommand causing early return in pipeline (PR #184028)

[Paul Kirth via llvm-commits]

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@@ -857,6 +899,9 @@ def _executeShCmd(cmd, shenv, results, timeoutHelper):
             else:
                 break
 
+        if handled_inproc_pipeline:
+            continue
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ilovepi wrote:

Why is this required? won't that prevent other builtins from working? Probably worth a comment if its necessary.

https://github.com/llvm/llvm-project/pull/184028