#711 fix bc bug in 1plus1D

[rtimms]

Description

Fixes a bug where boundary conditions were sometimes set incorrectly in 1plus1D models

Fixes #711

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ flake8
• All tests pass: $ python run-tests.py --unit
• The documentation builds: $ cd docs and then $ make clean; make html

You can run all three at once, using $ python run-tests.py --quick.

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

Merging #713 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #713      +/-   ##
==========================================
+ Coverage   98.18%   98.18%   +<.01%     
==========================================
  Files         175      175              
  Lines        9089     9090       +1     
==========================================
+ Hits         8924     8925       +1     
  Misses        165      165

Impacted Files	Coverage Δ
pybamm/discretisations/discretisation.py	99.71% <100%> (ø)	⬆️

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[valentinsulzer]

Struggling to get my head round this but it looks like you've thought about it carefully ...

[rtimms]

@tinosulzer is it a bit more clear what is going on now?

[valentinsulzer]

yep, thanks!