Fix resolution of weights filename in TMVATransform

Before this fix, the filename of the weights in TMVATransform was sometimes resolved (env vars expanded) but sometimes it wasn't, notably when passing it to ROOT.

This bug prevents building the functor cache in Moore when TMVATransform is used.

The positive effect of this bug fix is not observable in the nightlies, so we should probably pair it with a MR in Moore.

Thanks to @sstahl for reporting

added bug fix label

@jonrob, I assigned this to you to review as you changed it most recently.

This is a similar sympton to LHCb#47, but a different cause right?

mentioned in issue LHCb#47

added lhcb-head label

Seems fine to me.

unmarked as a Work In Progress

• [2020-06-14 00:13] Validation started with lhcb-head#2621
• [2020-06-15 00:16] Validation started with lhcb-head#2622
• [2020-06-16 00:10] Validation started with lhcb-gaudi-head-py3#386
• [2020-06-16 00:11] Validation started with lhcb-sanitizers#597
• [2020-06-16 00:12] Validation started with lhcb-dd4hep#553
• [2020-06-16 00:14] Validation started with lhcb-lcg-dev4#1314
• [2020-06-16 00:14] Validation started with lhcb-lcg-dev3#1300
• [2020-06-16 00:18] Validation started with lhcb-lcg-test#64
• [2020-06-16 00:19] Validation started with lhcb-gaudi-head#2633
• [2020-06-16 00:20] Validation started with lhcb-head#2623

added all-slots label and removed lhcb-head label

mentioned in merge request !731 (merged)

@rmatev Do you agree this is now OK to be merged ?

changed the description

yes, I'm able to build and use a functor cache locally, so let's merge

merged

mentioned in commit b0ad5598

unassigned @jonrob

added Functors label

resolved all threads