BLD: try harder to find errno in @network
Merge pull request #6172 from jreback/empty_frame

BUG: Consistency with dtypes in setting an empty DataFrame (GH6171)
BLD/TST: @network, SkipTest on certain exception messages, when no errno set
TST: set default socket timeout to 5 sec in pandas.io.tests SetUp()
Merge pull request #6174 from y-p/PR_more_network

More @network fixes
CLN: use assertEqual over assert_ for better exception messages
BUG/API: df['col'] = value and df.loc[:,'col'] = value are now completely equivalent;
         previously the .loc would not necessarily coerce the dtype of the resultant
         series (GH6149)