Ensure we're doing the right thing with adding paths to strings

[shlevy]

This isn't confusing at all:

nix-repl> { outPath = ./.; } + "/foo"
"/run/user/1000/home/foo"

nix-repl> ./. + "/foo"
/run/user/1000/home/foo

nix-repl> "foo" + ./.
"foo/nix/store/gy107asivi1cbisazsqyivmnrklifmqm-home"

nix-repl> "foo" + { outPath = ./.; }
"foo/nix/store/gy107asivi1cbisazsqyivmnrklifmqm-home"

Note especially that the return type of the second example is a path, not a string.

[mightybyte]

Pinging @kmicklas because this is currently using hackyStringIgnoreContext which I believe he is working on.

[Anton-Latukha]

hackyStringIgnoreContext are no longer hacky (#386 & such), the became normal.

From the above - only nix-repl> "foo" + ./. does not work, in fact looks like does not halt.