Fix notification image reloading

[Elv13]

It might work. I ran the code, but I don't have "real" tests for this right now.

[codecov[bot]]

Codecov Report

Attention: 16 lines in your changes are missing coverage. Please review.

Comparison is base (cb72c0a) 91.01% compared to head (98a8922) 90.99%. Report is 18 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3883      +/-   ##
==========================================
- Coverage   91.01%   90.99%   -0.02%     
==========================================
  Files         901      902       +1     
  Lines       57566    57744     +178     
==========================================
+ Hits        52392    52545     +153     
- Misses       5174     5199      +25     

Flag	Coverage Δ
gcov	90.99% <57.89%> (-0.02%)	:arrow_down:
luacov	93.70% <57.89%> (-0.02%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
lib/naughty/list/actions.lua	94.50% <ø> (ø)
lib/naughty/widget/icon.lua	92.40% <88.88%> (+0.09%)	:arrow_up:
lib/wibox/widget/imagebox.lua	90.80% <48.27%> (-5.63%)	:arrow_down:

... and 7 files with indirect coverage changes