Fix displaying of status code without a status message.

[isidentical]

Fixes #1300

[codecov-commenter]

Codecov Report

Merging #1301 (6f25c8e) into master (4d7d6b6) will decrease coverage by 0.61%.
The diff coverage is 95.40%.

❗ Current head 6f25c8e differs from pull request most recent head 895535c. Consider uploading reports for the commit 895535c to get more accurate results

@@            Coverage Diff             @@
##           master    #1301      +/-   ##
==========================================
- Coverage   97.28%   96.66%   -0.62%     
==========================================
  Files          67       85      +18     
  Lines        4235     6031    +1796     
==========================================
+ Hits         4120     5830    +1710     
- Misses        115      201      +86     

Impacted Files	Coverage Δ
tests/test_binary.py	100.00% <ø> (ø)
httpie/compat.py	31.11% <27.90%> (-68.89%)	⬇️
tests/conftest.py	77.14% <58.33%> (-9.82%)	⬇️
tests/test_ssl.py	91.01% <66.66%> (-3.93%)	⬇️
httpie/manager/__main__.py	82.35% <82.35%> (ø)
httpie/output/lexers/metadata.py	82.35% <82.35%> (ø)
httpie/output/lexers/http.py	86.36% <86.36%> (ø)
httpie/models.py	94.23% <90.00%> (-3.14%)	⬇️
tests/test_uploads.py	97.70% <92.59%> (-2.30%)	⬇️
httpie/manager/core.py	92.85% <92.85%> (ø)
... and 71 more

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[jkbrzt]

@isidentical not sure if you’ve noticed the subtle detail that there can be a space after the code in the phrase-less version. So all these are possible:

HTTP/1.1 200 OK
HTTP/1.1 200
HTTP/1.1 200<space>

It would be good to have explicit tests for the last variant as well.