There is a problem with /usr/share/bash-completion/perl (both in bash-completion-1.3-r2 and 2.1) - to get list of available completions it execute `man` command. Sometimes users have own replacement in ~/bin/man which show man pages using non-standard browsers/pagers like vim, and this result in starting vim in background while trying to get completions. I think it make sense to use `/usr/bin/man` instead of `man` to get completions.
*** This bug has been marked as a duplicate of bug 520030 ***
oops, not a duplicate
I'm sorry but this is not something I'm going to call supported. If you replace 'man' with something custom and incompatible with the original man, you get to keep the pieces. Hardcoding paths is a very bad idea, especially if the sole purpose is to workaround something broken on $PATH.