tests: stabilize `test-clonebundles-autogen.t` on Windows The problem was that the commands are spun up with `shell=True`, which uses `cmd.exe`, which doesn't understand `$foo` style variables. The HGCB variable expansion has to be delayed, because it's figured out right before launching the command. We could probably add a conditional for Windows, and rewrite the config to use `%foo%` style variables, but it's more maintainable to just wrap the command in a bash shell invocation. The forward style slashes in the path are needed to avoid accruing double backslashes (when switching between shells- the url template seems fine). Also need to strong quote the command so that the double quotes don't get stripped off of `$HGCB_BUNDLE_PATH`, which results in: sh: 1: Syntax error: Unterminated quoted string abort: command returned status 2: sh -c "cp $HGCB_BUNDLE_PATH $TESTTMP/final-upload/"