[package] fix error handling with allow_empty (#56190)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56190
Previously, if we had some code that did the following:
```
- pattern A, allow_empty=False
- save module B, but throws an exception for whatever reason
- save module that causes match against A
```
Then the resulting behavior would be:
1. exception thrown, which triggers `__close__` on `PackageExporter`
2. `PackageExporter` checks that all patterns are matched against, and sees that A was not matched.
3. Error is raised that we didn't match against pattern A.
This is confusing, since the *real* error that caused packaging to fail
occurred when trying to package module B, but it's being hidden by the
error about module A (even though if packaging module B had succeeded,
there would be no error).
Change it so that the behavior looks like:
1. exception thrown, which triggers `__close__` on `PackageExporter`
2. `PackageExporter` recognizes that an exception is happening and
immediately just returns control flow to the caller to handle the "real"
exception.
Differential Revision: D27803988
Test Plan: Imported from OSS
Reviewed By: guangyuwang
Pulled By: suo
fbshipit-source-id: f67b2e96165a0547c194a8bef1af1c185452173e
