Files with "build" prefix are gitignored

[saprykinoff]

Steps to reproduce

git clone --depth 1 https://github.com/userver-framework/service_template.git
git clone --depth 1 https://github.com/userver-framework/userver.git service_template/third_party/userver 
cd service_template
cd src
touch buildprefix.cpp
git status

Observable behaviour

On branch develop
Your branch is up to date with 'origin/develop'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	../third_party/userver/

nothing added to commit but untracked files present (use "git add" to track)

Expected behaviour

On branch develop
Your branch is up to date with 'origin/develop'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	buildprefix.cpp
	../third_party/userver/

nothing added to commit but untracked files present (use "git add" to track)

[Antony Polukhin]

Fixed