with HEAD (5c885c2 ) on branch Dev_1.0, pip failed to install cryptography and twisted.

gistfile1.txt

(.venv) bzu@bruce-laptop:~/project/FortiCloudPlatform/apps$ git branch -av
* Dev_1.0                                                5c885c2 Merge branch 'Dev_1.0_feature_saml_sso-squashed' into  

error message 


x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include/python3.5m -I/home/bzu/project/FortiCloudPlatform/apps/portal/.venv/include/python3.5m -c build/temp.linux-x86_64-3.5/_openssl.c -o build/temp.linux-x86_64-3.5/build/temp.linux-x86_64-3.5/_openssl.o
  build/temp.linux-x86_64-3.5/_openssl.c:12:24: fatal error: pyconfig.h: No such file or directory
  compilation terminated.
  error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
  
  ----------------------------------------
  Failed building wheel for cryptography
....
x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include/python3.5m -I/home/bzu/project/FortiCloudPlatform/apps/portal/.venv/include/python3.5m -c src/twisted/test/raiser.c -o build/temp.linux-x86_64-3.5/src/twisted/test/raiser.o
  src/twisted/test/raiser.c:4:20: fatal error: Python.h: No such file or directory
  compilation terminated.
  error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
  
  ----------------------------------------
  Failed building wheel for twisted
......

   x86_64-linux-gnu-gcc -pthread -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -g -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -I/usr/include/python3.5m -I/home/bzu/project/FortiCloudPlatform/apps/portal/.venv/include/python3.5m -c src/twisted/test/raiser.c -o build/temp.linux-x86_64-3.5/src/twisted/test/raiser.o
    src/twisted/test/raiser.c:4:20: fatal error: Python.h: No such file or directory
    compilation terminated.
    error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
    
    ----------------------------------------
Command "/home/bzu/project/FortiCloudPlatform/apps/portal/.venv/bin/python3 -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-wdbbttaq/twisted/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-7ol5_5m0-record/install-record.txt --single-version-externally-managed --compile --install-headers /home/bzu/project/FortiCloudPlatform/apps/portal/.venv/include/site/python3.5/twisted" failed with error code 1 in /tmp/pip-build-wdbbttaq/twisted/

Fix by:
deactivate
#_ echo "alias python=python3.5" > ~/.bashrc
#_ echo "alias pip=pip3" > ~/.bashrc
#_ source ~/.bashrc
sudo apt-get install python3
sudo apt-get install python3-pip
pip install --upgrade pip

source .venv/bin/activate
pip install -r requirements.txt