Specifically, when searching stdin, if the current directory has a
directory named `-`, then the `--with-filename` flag would automatically
be turned on. This is because `--with-filename` is automatically enabled
when ripgrep is given a single path that is a directory. When ripgrep is
given empty arguments, and if it is searching stdin, then its default
path list is just simple `["-"]`. The `is_dir` check passes, and
`--with-filename` gets enabled.
This commit fixes the problem by checking whether the path is `-` first.
If so, then we assume it isn't a directory. This is fine, since if it is
a directory and one asks to search it explicitly, then ripgrep will
interpret `-` as stdin anyway (which is arguably a bug on its own, but
probably not one worth fixing).
Fixes#1223, Closes#1292
9268ff8e8d