tests/test-gendoc-ja.t

posix: always seek to EOF when opening a file in append mode

Python 3 already does this, so skip it there.

Consider the program:

   #include <stdio.h>

   int main() {
     FILE *f = fopen("narf", "w");
     fprintf(f, "narf\n");
     fclose(f);

     f = fopen("narf", "a");
     printf("%ld\n", ftell(f));
     fprintf(f, "troz\n");
     printf("%ld\n", ftell(f));

     return 0;
   }

on macOS, FreeBSD, and Linux with glibc, this program prints

   5
   10

but on musl libc (Alpine Linux and probably others) this prints

   0
   10

By my reading of
https://pubs.opengroup.org/onlinepubs/009695399/functions/fopen.html
this is technically correct, specifically:

> Opening a file with append mode (a as the first character in the
> mode argument) shall cause all subsequent writes to the file to be
> forced to the then current end-of-file, regardless of intervening
> calls to fseek().

in other words, the file position doesn't really matter in append-mode
files, and we can't depend on it being at all meaningful unless we
perform a seek() before tell() after open(..., 'a'). Experimentally
after a .write() we can do a .tell() and it'll always be reasonable,
but I'm unclear from reading the specification if that's a smart thing
to rely on. This matches what we do on Windows and what Python 3 does
for free, so let's just be consistent. Thanks to Yuya for the idea.

#require docutils gettext

  $ $TESTDIR/check-gendoc ja
  checking for parse errors
  \xe8\xa4\x87\xe8\xa3\xbd\xef\xbc\x8f\xe6\x94\xb9\xe5\x90\x8d\xe3\x81\xab\xe9\x96\xa2\xe3\x81\x99\xe3\x82\x8b\xe5\xb1\xa5\xe6\xad\xb4\xe4\xbf\x9d\xe5\xad\x98\xe3\x81\xae\xe3\x81\x9f\xe3\x82\x81\xe3\x81\xab git \xe5\xb7\xae\xe5\x88\x86\xe5\xbd\xa2\xe5\xbc\x8f\xe3\x82\x92\xe4\xbd\xbf\xe7\x94\xa8(-g/--git \xe6\x8c\x87\xe5\xae\x9a\xe3\x82\x84 \xe8\xa8\xad\xe5\xae\x9a\xe3\x83\x95\xe3\x82\xa1\xe3\x82\xa4\xe3\x83\xab\xe3\x81\xa7\xe3\x81\xae [diff] git=1 \xe8\xa8\x98\xe8\xbf\xb0)\xe3\x81\x99\xe3\x82\x8b\xe3\x81\xae\xe3\x81\xa7\xe3\x81\x82\xe3\x82\x8c\xe3\x81\xb0\xe3\x80\x81 add/remove/copy/rename \xe3\x81\xa8\xe3\x81\x84\xe3\x81\xa3\xe3\x81\x9f hg \xe3\x81\xae\xe3\x82\xb3\xe3\x83\x9e\xe3\x83\xb3\xe3\x83\x89\xe3\x81\xab\xe3\x82\x88\xe3\x82\x8b\xe5\xb1\xa5\xe6\xad\xb4\xe8\xa8\x98\xe9\x8c\xb2\xe3\x82\x82\xe3\x80\x81 \xe9\x80\x9a\xe5\xb8\xb8\xe3\x81\xa8\xe5\xa4\x89\xe3\x82\x8f\xe3\x82\x8a\xe3\x81\xaa\xe3\x81\x8f\xe6\xa9\x9f\xe8\x83\xbd\xe3\x81\x97\xe3\x81\xbe\xe3\x81\x99\xe3\x80\x82 git \xe5\xb7\xae\xe5\x88\x86\xe5\xbd\xa2\xe5\xbc\x8f\xe3\x81\xae\xe8\xa9\xb3\xe7\xb4\xb0\xe3\x81\xab\xe9\x96\xa2\xe3\x81\x97\xe3\x81\xa6\xe3\x81\xaf\xe3\x80\x81 'help diffs' \xe3\x82\x92\xe5\x8f\x82\xe7\x85\xa7\xe3\x81\x97\xe3\x81\xa6\xe3\x81\x8f\xe3\x81\xa0\xe3\x81\x95\xe3\x81\x84\xe3\x80\x82 (esc)
  warning: please use " instead of ' for hg ... "..."