Invalid read: Multi::close called twice

[DBLouis]

Multi::close is called a second time in the Drop impl: https://docs.rs/curl/0.4.29/src/curl/multi.rs.html#728-732
Valgrind reports the following:

==5851== Invalid read of size 8
==5851==    at 0x560D4A5: curl_multi_cleanup (in /usr/lib/libcurl.so.4.6.0)
==5851==    by 0x4E75621: curl::multi::Multi::close (multi.rs:705)
==5851==    by 0x4E756AA: <curl::multi::Multi as core::ops::drop::Drop>::drop (multi.rs:730)
==5851==    by 0x4D86E76: core::ptr::drop_in_place (mod.rs:177)
==5851==    by 0x4D87D96: core::ptr::drop_in_place (mod.rs:177)
==5851==    by 0x4DD41B3: isahc::agent::AgentContext::run (agent.rs:495)

Removing the call to close seems to fix it, however some memory leaks remain.

[codecov]

Codecov Report

Merging #198 into master will decrease coverage by 0.46%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #198      +/-   ##
==========================================
- Coverage   69.85%   69.38%   -0.47%     
==========================================
  Files          33       33              
  Lines        1874     1852      -22     
==========================================
- Hits         1309     1285      -24     
- Misses        565      567       +2     

Impacted Files	Coverage Δ
src/agent.rs	69.03% <ø> (-2.01%)	⬇️
src/metrics.rs	24.39% <0.00%> (-8.95%)	⬇️
src/handler.rs	74.37% <0.00%> (-1.14%)	⬇️
src/auth.rs	60.93% <0.00%> (-0.97%)	⬇️
src/text.rs	70.68% <0.00%> (ø)
src/config/dns.rs	0.00% <0.00%> (ø)
src/client.rs	62.34% <0.00%> (+0.51%)	⬆️
src/cookies/mod.rs	85.00% <0.00%> (+2.20%)	⬆️

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[sagebind]

Hmm, yeah that's no good! This should probably be fixed upstream as well. Multi::close should probably have taken self, not &self. For now, its probably OK to merge this as-is until upstream is fixed, at which point we can put the manual call back.

The purpose of calling close manually was to ensure that any errors that that function returned would be visible instead of ignored.

[sagebind]

Thanks! 👏