test: preserve the existing module policy config for testrepohg resuse...
test: preserve the existing module policy config for testrepohg resuse
The test runner is, righfully, setting HGMODULEPOLICY to match the flavor
requests to run the tests. However this mess with the `testrepohg` ability to
run properly, as the newly set policy might be incompatible with its
installation, or its ability to read the test repo.
So we preserve the initial value in a dedicated variable and use it in the
`testrepohg` helper.
