Log when terminated

The twarc command catches SIGTERM so that users can ctrl-c to stop the
process. But it did so quietly, which could be perplexing when users put
twarc into the background and then logged out (which can cause SIGTERM
being sent to the process). To aid in diagnosing when/why things stop
this commit adds logging to when twarc is shutting down. fixes #319

setup.py

@@ -4,7 +4,7 @@
 from setuptools import setup
 
 # Also in twarc/__init__.py
-__version__ = '1.8.1'
+__version__ = '1.8.2'
 
 with open("README.md") as f:
     long_description = f.read()

twarc/__init__.py

@@ -1,4 +1,4 @@
-__version__ = '1.8.1'  # also in setup.py
+__version__ = '1.8.2'  # also in setup.py
 
 from .client import Twarc
 from .command import main

twarc/command.py

@@ -65,8 +65,11 @@ def main():
         format="%(asctime)s %(levelname)s %(message)s"
     )
 
-    # catch ctrl-c so users don't see a stack trace
-    signal.signal(signal.SIGINT, lambda signal, frame: sys.exit(0))
+    # log and stop when process receives SIGINT
+    def stop(signal, frame):
+        log.warn('process received SIGNT, stopping')
+        sys.exit(0)
+    signal.signal(signal.SIGINT, stop)
 
     if command == "version":
         print("twarc v%s" % __version__)