fix sync-client async connect bugs

[matyhtf]

No description provided.

[codecov]

Codecov Report

Merging #4152 (4178a21) into master (b3883ea) will increase coverage by 0.04%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master    #4152      +/-   ##
==========================================
+ Coverage   48.74%   48.78%   +0.04%     
==========================================
  Files          71       71              
  Lines       14280    14282       +2     
==========================================
+ Hits         6961     6968       +7     
+ Misses       7319     7314       -5     

Impacted Files	Coverage Δ
src/network/client.cc	47.09% <44.44%> (+0.52%)	⬆️
src/network/dns.cc	86.75% <100.00%> (+0.06%)	⬆️
src/os/async_thread.cc	68.85% <0.00%> (-0.44%)	⬇️
src/server/manager.cc	30.88% <0.00%> (ø)
src/protocol/base.cc	63.15% <0.00%> (+1.97%)	⬆️

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