[regression] ambiguous local variable

[Mark-Simulacrum]

For example:

INFO] [stderr] error[E0659]: `time` is ambiguous (glob import vs glob import in the same module)
[INFO] [stderr]    --> src/main.rs:257:13
[INFO] [stderr]     |
[INFO] [stderr] 257 |     let mut time = Local::now();
[INFO] [stderr]     |             ^^^^ ambiguous name
[INFO] [stderr]     |
[INFO] [stderr] note: `time` could refer to the function imported here
[INFO] [stderr]    --> src/main.rs:4:5
[INFO] [stderr]     |
[INFO] [stderr] 4   | use libc::*;
[INFO] [stderr]     |     ^^^^^^^
[INFO] [stderr]     = help: consider adding an explicit import of `time` to disambiguate
[INFO] [stderr] note: `time` could also refer to the function imported here
[INFO] [stderr]    --> src/main.rs:11:5
[INFO] [stderr]     |
[INFO] [stderr] 11  | use xcb_bindings::*;
[INFO] [stderr]     |     ^^^^^^^^^^^^^^^
[INFO] [stderr]     = help: consider adding an explicit import of `time` to disambiguate
[INFO] [stderr] 

• https://crater-reports.s3.amazonaws.com/beta-1.44-1/beta-2020-04-26/gh/RoBaaaT.rusty-pt/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.44-1/beta-2020-04-26/gh/sam-barr.sam-bar/log.txt

cc @petrochenkov

[petrochenkov]

This is a regression from #70006.

#70006 produced an ambiguity error even if the binding is syntactically unambiguous (e.g. mut time like in the example above) for some future-compatibility reasons (#33118 (comment)), but it can be easily tweaked to not produce it because backward-compatibility is more important.

[petrochenkov]

Fixed in #71846.