Handle nonzero status in addUPI telemetry (fixes #478)

[aptiko]

Checklist:

• [ ] All tests are passing
• [ ] I have added any necessary documentation and/or release notes
• [ ] I have followed the commit message guidelines and the "before submitting a pull request" guidelines
• [ ] If I introduced (or abolished) any third-party library, I will write a short paragraph in this PR according to the guidelines
• [ ] I have removed all obsoleted code

[codecov[bot]]

Codecov Report

Merging #502 (7cd8dc3) into master (491c887) will increase coverage by 0.01%. The diff coverage is 100.00%.

:exclamation: Current head 7cd8dc3 differs from pull request most recent head 92d0a54. Consider uploading reports for the commit 92d0a54 to get more accurate results

@@            Coverage Diff             @@
##           master     #502      +/-   ##
==========================================
+ Coverage   98.20%   98.21%   +0.01%     
==========================================
  Files          41       41              
  Lines        2119     2133      +14     
==========================================
+ Hits         2081     2095      +14     
  Misses         38       38              

Files Changed	Coverage Δ
enhydris/telemetry/types/addupi.py	100.00% <100.00%> (ø)

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