Fix issue #3055 (project search with unmatched parentheses)

Fixes issue #3055 (closed). The problem happens because the search query was being escaped using Shellwords.shellescape.

Before the fix, this was happening:

git grep -i -n --before-context 2 --after-context 2 'foo\(' master;
fatal: 'foo\(': Unmatched ( or \(

After the fix, no more errors:

git grep -i -n --before-context 2 --after-context 2 'foo(' master;