Improve how reference catalog is expanded

[mcara]

This PR addresses the issue JP-3468 (excerpt):

When running the TweakRegStep with expand_refcat=True, if aligning an image fails, its sources are still added to the reference catalog. This breaks the astrometric consistency of the reference catalog, and the next image(s) can lock onto these unaligned sources (or just not match and add even more unaligned sources). This can cause a cascade of misaligned images that can report the alignment as successful.

Reported by @Vb2341

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (26703f8) 95.25% compared to head (48907b2) 93.79%.

Files	Patch %	Lines
tweakwcs/imalign.py	94.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #195      +/-   ##
==========================================
- Coverage   95.25%   93.79%   -1.47%     
==========================================
  Files          11       11              
  Lines        1939     1982      +43     
==========================================
+ Hits         1847     1859      +12     
- Misses         92      123      +31     

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[mcara]

JWST regression tests running here: https://plwishmaster.stsci.edu:8081/job/RT/job/JWST/2727/

[mcara]

@Vb2341 Could you, please, confirm that this solves the issue? You can install this code with

pip install git+https://github.com/mcara/tweakwcs.git@dont-add-failed-catalogs-to-expanded-refcat

[hbushouse]

Just adding a reference to JP-3468

[hbushouse]

Shouldn't this be "0.8.6", as opposed to "0.8.7"?