In a test, I uploaded a pdf, and several files were derived from it.
After removing the pdf, the derived files went away after approximatly
half an hour. This window does not seem worth warning about every time.
Documented it in the tip.
Removal works, only derives are a potential issue, so allow removing
with a warning. This way, unexporting a file works, and behavior is
consistent with IA remotes whether or not exporttree=yes.
Also tested exporting filenames containing unicode, spaces, underscores.
All worked, despite the IA's faq saying it doesn't.
This commit was sponsored by Trenton Cronholm on Patreon.
It opens a http connection per file exported, but then so does git
annex copy --to s3.
Decided not to munge exported filenames for IA. Too large a chance of
the munging having confusing results. Instead, export of files not
supported by IA, eg with spaces in their name, will fail.
This commit was supported by the NSF-funded DataLad project.
