Avoid emptying all the minimisers if hitting minimum at the begining

[Suavesito-Olimpiada]

fix #62

[dpsanders]

Thanks! Could you add your example as a test case please?

[codecov-commenter]

Codecov Report

Merging #63 (6a5a7b1) into master (9bddaed) will increase coverage by 1.15%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #63      +/-   ##
==========================================
+ Coverage   91.91%   93.06%   +1.15%     
==========================================
  Files           4        4              
  Lines          99      101       +2     
==========================================
+ Hits           91       94       +3     
+ Misses          8        7       -1     

Impacted Files	Coverage Δ
src/HeapedVectors.jl	98.07% <100.00%> (ø)
src/SortedVectors.jl	75.00% <100.00%> (+2.77%)	⬆️
src/optimise.jl	100.00% <0.00%> (+3.57%)	⬆️

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[Suavesito-Olimpiada]

Test added based on the simpler case found in this comment from the issue #62.

[Suavesito-Olimpiada]

bump (?)

[lucaferranti]

Apologies @Suavesito-Olimpiada for the veery long delay with this. It fell off my radar, although it is not of course a valid excuse. I think this PR looks good, could you still bump the patch version in the Project.toml, so we can release a new version with the bug fix? :)

[Suavesito-Olimpiada]

@lucaferranti I bumped the version to v0.4.6, but there is a conflict to resolve.