Always consume the whole format string

[vhf]

As highlighted here by @rauschma , there seems to be a bug in formatWithOptions:

node -r esm -e "const {format} = require('util'); console.log(format('%s%%', 99))"
99%%

formatWithOptions stops consuming the format string and simply copies the rest of its input instead of processing it as soon as all formats have been replaced by their arg. In the above case, there's one format and one arg so the rest (%%) gets copied. Instead, %% should be processed as % as stated in node.js docs.

(Since it's a special case (the only 'format' that takes 0 arg), this PR could be made a bit more efficient by having special detection for this case and break out early as it was before but after making sure this case is handled. Not sure it's worth it though, it would add quite a few lines of code thus making it more complex for a seemingly small benefit.)

[rauschma]

Possibly: write a unit test to prevent a regression.

[vhf]

I thought about it and looked for unit tests for this file/grepped the function name but couldn't find any, I'll add one if there are already some.

[jdalton]

Patch 5cd561d; Test 1d93fb3.

Update:

esm v3.2.19 is released 🎉