Use -e option instead of -c option (rake rdoc task).

[kennyj]

If we set ISO-8859-1 (excepting utf-8) to LANG environment variable, rake rdoc task is not work fine.

$ export LANG=en_US.ISO-8859-1 ★
$ bundle exec rake rdoc
Parsing sources...
100% [644/644]  RDOC_MAIN.rdoc

Generating SDoc format into /home/kennyj/rails/doc/rdoc...
rake aborted!
incompatible encoding regexp match (UTF-8 regexp with ISO-8859-1 string)

Tasks: TOP => rdoc => doc/rdoc/index.html
(See full trace by running task with --trace)

It seems that "-c" option is not work fine.
With this pull request (instead of using -e (encoding) option).

$ bundle exec rake rdoc
Parsing sources...
100% [644/644]  RDOC_MAIN.rdoc

Generating SDoc format into /home/kennyj/rails/doc/rdoc...

Files:       644

Classes:     369 ( 214 undocumented)
Modules:     353 ( 236 undocumented)
Constants:   214 ( 193 undocumented)
Attributes:  329 ( 309 undocumented)
Methods:    3443 (1653 undocumented)

Total:      4708 (2605 undocumented)
 44.67% documented

Elapsed: 323.7s

I thinks that this issue is related to GH #3743 .

[spastorino]

@kennyj does we need to backport this PR to 3.1? I've already pushed it to 3-2-stable

[kennyj]

@spastorino
I think that 3-1-stable has same problem, and ｔhis commit seems to be effective (in my environment).
Please merge this PR to 3.1.

p.s.
I think that I fixed 3743.