Multiple repeated fields are allowed

[topherCantrell]

The protobuffer comments have been corrected here:
https://github.com/protocolbuffers/protobuf/blob/master/src/google/protobuf/field_mask.proto#L85-L86

The restriction was intended for the path string itself and not the
entire mask. There can be only one repeated field in a path string, and
when we get to it, the path string is done.

We found ourselves using multiple repeated fields in a message.

This fixes:

#1766

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[topherCantrell]

@googlebot I signed it!

[codecov-io]

Codecov Report

Merging #1921 (4b26c3e) into master (c94a79d) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1921      +/-   ##
==========================================
- Coverage   57.96%   57.96%   -0.01%     
==========================================
  Files          34       34              
  Lines        3771     3766       -5     
==========================================
- Hits         2186     2183       -3     
+ Misses       1311     1310       -1     
+ Partials      274      273       -1     

Impacted Files	Coverage Δ
runtime/fieldmask.go	85.00% <100.00%> (+1.92%)	⬆️

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[irridia]

Thanks @topherCantrell! This was still on my list, but hadn't yet made it to the top.

[johanbrandhorst]

Thanks for this! Could you please add a new test case that exhibits the new behaviour too?

[topherCantrell]

There we go. A test for multiple repeats.

[johanbrandhorst]

Nice, thanks a lot for this!