Make pull return non-zero error code when some downloads failed

[seth2810]

#2236

[ttaylorr]

@seth2810 this looks good. In terms of forcing an error to occur during command execution, you can instruct the Git server we run during tests to return an error by using a special "contentHandler".

• You can add the content handler here, and then
• Check for presence of the content handler here.

[technoweenie]

@ttaylorr I'm tweaking the error message and fixing this up to get this out in today's release.

@seth2810: Thanks for getting this started!

[ttaylorr]

@ttaylorr I'm tweaking the error message and fixing this up to get this out in today's release.

@technoweenie sounds great, thanks!

[technoweenie]

@seth2810: your pull test had the right mindset, but it was using some undefined local variables: $reponame, $b_oid, and $contents_oid. I fixed the test by declaring them in the individual test, and fixing the cd ../clone line too.

@ttaylorr's idea would've worked too, but I prefer tests that don't rely on special test server behavior if we can avoid it.