Strings with a number ending in eight or nine are dumped as integers

[albertca]

Here's a small snippet to reproduce the problem:

import yaml

for x in range(0, 12):
    yaml.dump({'a': '%06s' % x})

And here the output:

"a: '000000'\n"
"a: '000001'\n"
"a: '000002'\n"
"a: '000003'\n"
"a: '000004'\n"
"a: '000005'\n"
"a: '000006'\n"
"a: '000007'\n"
'a: 000008\n'
'a: 000009\n'
"a: '000010'\n"
"a: '000011'\n"

For some reason numbers ending in 8 or 9 are dumped as integers, but they should be strings just like the rest of the numbers. Using larger numbers shows that all numbers ending in 8 or 9 are always dumped as integers.

[albertca]

Although I don't completely understand the reason why it's exported like this I realize that it does not cause any problem in loading again the generated YAML, which loads as string, so I'm closing the issue.

Sorry for the noise.

[perlpunk]

That looks like the issue was supposed to land in https://github.com/yaml/pyyaml ?

[perlpunk]

I transferred the issue to pyyaml.
There are already existing issues here that discuss this. 000008 is not an integer because pyyaml implements YAML 1.1 currently, and scalars starting with a zero are resolved as octal numbers if they only contain 0-7. 8 and 9 are not octal digits.