Bugzilla

A hang occurs when running `./mach vendor media/libyuv/moz.yaml --patch-mode only`. A `^C^C` yields a python trace indicating that the hang is occurring during the patch command execution. The user is prompted for input when I run that command locally:

```
$ patch -p1 --directory media/libyuv/libyuv/ --input $HOME/dev/mozilla-unified/media/libyuv/fix_build_errors. patch --no-backup-if-mismatch
patching file 'include/libyuv/row.h'
Reversed (or previously applied) patch detected!  Assume -R? [y]
```


`patch --version` yields `patch 2.0-12u11-Apple`

A hang occurs when running `./mach vendor media/libyuv/moz.yaml --patch-mode only`. A `^C^C` yields a python trace indicating that the hang is occurring during the patch command execution. The user is prompted for input when I run that command locally:

```
$ patch -p1 --directory media/libyuv/libyuv/ --input $HOME/dev/mozilla-unified/media/libyuv/fix_build_errors. patch --no-backup-if-mismatch
patching file 'include/libyuv/row.h'
Reversed (or previously applied) patch detected!  Assume -R? [y]
```


`patch --version` yields `patch 2.0-12u11-Apple`

This triggered by user error. I ran `mach vendor` with `--patch-mode=only` before running it with `--patch-mode=none`.  In that case, the prompt that patch presented was exactly what it should have done. `mach vendor` could point one in the right direction if `patch` prompts in this way.