Get the file diff's included in the perforce P4Python api structured data

hack.py

## The Perforce P4Python api and p4 -G (marshalled data) do not return the diff data shown when you use the 'p4 describe' 
## command to describe a changeset. You need to run the P4Python API in untagged mode. But then you have to parse things yourself.
## But the untagged data is partially structured. Each piece of data is included with embedded newlines. The file diff section has each
## header and then the diff data. The tagged data returned from the P4Python API has each file's data split into independent lists.
## So you get the file names and revisions each as independent lists. But the file diff section may not include all files. Some
## might be binary, some might be too large to diff (by server settings), etc. So you want to add two new lists to the tagged
## output, one for the headers and one for the diff raw data, but you want them to be aligned with the depotFiles listing.
## and using '' has sentinal place holders. So here we go:

import P4
import itertools
p4 = P4.P4() # assume P4PORT, etc set in env.
p4.connect()
desc = p4.run_describe(12345)[0]
with p4.while_tagged(False):
  result = p4.run_describe(12345)

# 5 lines of simple text processing.
r = itertools.dropwhile(lambda x: x!='\nDifferences ...\n', result)
r.next() # drop off the sentinal
rr = {x.split(' ',1)[1].rsplit('#',1)[0] : (x,y) for x,y in itertools.izip(r,r)}
desc['diffHeader'] = [ rr.get(df, ('',''))[0] for df in desc['depotFile'] ]
desc['diffData'] = [ rr.get(df, ('',''))[1] for df in desc['depotFile'] ]