cmake errors during the build

[Synoecium]

I did everything step-by-step from install guide and got these errors. I used commands git submodule init and git submodule update, so it isn't a problem source.
sa@sa-VirtualBox:~/cpp-netlib/build$ cmake -DCMAKE_BUILD_TYPE=Release ..
-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/g++
-- Check for working CXX compiler: /usr/bin/g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for pthread.h
-- Looking for pthread.h - found
-- Looking for pthread_create
-- Looking for pthread_create - not found
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - found
-- Found Threads: TRUE
-- Boost version: 1.58.0
-- Found the following Boost libraries:
-- system
-- thread
-- chrono
-- date_time
-- atomic
-- Found OpenSSL: /usr/lib/x86_64-linux-gnu/libssl.so;/usr/lib/x86_64-linux-gnu/libcrypto.so (found version "1.0.2g")
-- Performing Test HAVE_STD11
-- Performing Test HAVE_STD11 - Success
C++ Flags: -Wall -std=c++11 -std=c++11 -Wall -Werror link flags:
-- Configuring tests
CMake Error at deps/uri/CMakeLists.txt:85 (add_subdirectory):
The source directory

/home/sa/cpp-netlib/deps/uri/deps/googletest

does not contain a CMakeLists.txt file.

Configuring documentation
-- Found Doxygen: /usr/bin/doxygen (found version "1.8.11")
-- Found PythonInterp: /usr/bin/python (found version "2.7.12")
CMake Error at CMakeLists.txt:136 (add_subdirectory):
The binary directory

/home/sa/cpp-netlib/build/deps/uri/test

is already used to build a source directory. It cannot be used to build
source directory

/home/sa/cpp-netlib/deps/uri/test

Specify a unique binary directory name.

-- Configuring incomplete, errors occurred!
See also "/home/sa/cpp-netlib/build/CMakeFiles/CMakeOutput.log".
See also "/home/sa/cpp-netlib/build/CMakeFiles/CMakeError.log".

[alexBraidwood]

cd into /home/sa/cpp-netlib/deps/uri and run git submodule update --init --recursive - see if that does the trick. My mistake, this is actually a bug. So, there's two options here, in uri/CMakeLists.txt you can add a guard to not include gtest twice:

if (NOT TARGET gtest AND NOT TARGET gtestmain)
  add_subdirectory(deps/googletest)
endif()

Or just turn off tests:
option(Uri_BUILD_TESTS "Build the URI tests." OFF)

[LiSongMWO]

This seems to be a dupe of #849