This commit is targeted at further improving the error messages
generated from git errors. For authentication errors the actual URL
fetched is now printed out as well if it's different from the original
URL. This should help handle `insteadOf` logic where SSH urls are used
instead of HTTPS urls and users can know to track that down.
Otherwise the logic about recommending `net.git-fetch-with-cli` was
tweaked a bit and moved to the same location as the rest of our error
reporting.
Note that a change piggy-backed here as well is that `Caused by:` errors
are now automatically all tabbed over a bit instead of only having the
first line tabbed over. This required a good number of tests to be
updated, but it's just an updated in renderings.
There is a complex issue where `cargo test -Zfeatures=dev_dep` was
building things incorrectly if there was a binary executable. The issue
is that lib.rs needed to be built twice (once linked against normal
dependencies, once against dev dependencies), but the current Unit
structure can't distinguish between the two, and thus it was picking the
wrong one.
Instead of allowing `cargo test` to build binaries without
dev-dependency features, just link main.rs against the
dev-dependency-unified versions.
We may need to revisit this in the future, but for now it is not clear
what people want or how this should work. Fixing this would require
substantial changes to how unit dependencies are computed (to properly
handle deduplication), so for now we'll use a simpler solution. It would
also mean `cargo test` would take longer on some projects (because it
would need to build the library 3 times instead of twice).
