Don't run apt-cache if /etc/lsb-release exists.

Since /etc/lsb-release overrides detected information, there's no
need to try and detect that information if lsb-release contains
everything we need.  This saves us calling the hugely expensive
apt-cache.

1 files changed, 9 insertions, 3 deletions

diff --git a/lsb_release.py b/lsb_release.py
index 5c6cb9a..9208858 100644
--- a/lsb_release.py
+++ b/lsb_release.py
@@ -284,9 +284,15 @@ def get_lsb_information():
     return distinfo
 
 def get_distro_information():
-    distinfo = guess_debian_release()
-    distinfo.update(get_lsb_information())
-    return distinfo
+    lsbinfo = get_lsb_information()
+    # OS is only used inside guess_debian_release anyway
+    for key in ('ID', 'RELEASE', 'CODENAME', 'DESCRIPTION',):
+        if key not in lsbinfo:
+            distinfo = guess_debian_release()
+            distinfo.update(lsbinfo)
+            return distinfo
+    else:
+        return lsbinfo
 
 def test():
     print get_distro_information()