"DYLD_LIBRARY_PATH", // must be preserved on macOS systems to find shared libraries
		"LD_LIBRARY_PATH",   // must be preserved on Unix systems to find shared libraries
		"LIBRARY_PATH",      // allow override of non-standard static library paths
		"PYTHONPATH",        // may be needed by hg to find imported modules
	} {
		if v, ok := os.LookupEnv(k); ok {
			env = append(env, k+"="+v)
		}
	}

	"WINDIR",             // must be preserved on Windows to be able to run PowerShell command; golang.org/issue/30711
	"LD_LIBRARY_PATH",    // must be preserved on Unix systems to find shared libraries
	"LIBRARY_PATH",       // allow override of non-standard static library paths
	"C_INCLUDE_PATH",     // allow override non-standard include paths
	"CC",                 // don't lose user settings when invoking cgo