Add libyaml-dev dependency

[ValdikSS]

No description provided.

[codecov-io]

Codecov Report

Merging #420 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #420      +/-   ##
==========================================
- Coverage   88.02%   88.01%   -0.02%     
==========================================
  Files         146      146              
  Lines       27578    27578              
  Branches     3921     3921              
==========================================
- Hits        24275    24272       -3     
- Misses       2599     2601       +2     
- Partials      704      705       +1

Impacted Files	Coverage Δ
src/allmydata/mutable/servermap.py	93.55% <0%> (-0.65%)	⬇️
src/allmydata/web/status.py	83.16% <0%> (-0.23%)	⬇️
src/allmydata/immutable/layout.py	90.55% <0%> (ø)	⬆️
src/allmydata/immutable/upload.py	96.34% <0%> (+0.09%)	⬆️
src/allmydata/stats.py	86.2% <0%> (+0.86%)	⬆️

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[warner]

cool, thanks. I'll land this (in rebased form) in a moment. It's a pity this is necessary.. it'd be nice if there were a way to make PyYAML use the pure-python implementation (instead of linking against a C library), especially since we don't really need it to be fast. But if PyYAML decides to use libyaml, for whatever reason, then you're right we need the development headers to be installed.

[ValdikSS]

Please wait a moment, it could be my fault. I'll recheck it in some hours if it's really needed. It could be that pip failed to install python version of yaml.