[compiler-rt] Reapply "[compiler-rt] Default to Lit's Internal Shell (#168232)" (PR #168760)

[Florian Mayer via llvm-commits]

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@@ -113,16 +113,18 @@ def push_dynamic_library_lookup_path(config, new_path):
         config.environment[dynamic_library_lookup_var] = new_ld_library_path_64
 
 
+# TODO: Consolidate the logic for turning on the internal shell by default for all LLVM test suites.
+# See https://github.com/llvm/llvm-project/issues/106636 for more details.
+#
 # Choose between lit's internal shell pipeline runner and a real shell.  If
 # LIT_USE_INTERNAL_SHELL is in the environment, we use that as an override.
 use_lit_shell = os.environ.get("LIT_USE_INTERNAL_SHELL")
 if use_lit_shell:
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fmayer wrote:

or even `use_lit_shell == "0"`, because `None` doesn't equal any string.

https://github.com/llvm/llvm-project/pull/168760