convert: fix marshalling in P4 convert extension to use a binary stream The Perforce convert extension uses the p4 -G command line option and marshal.load to obtain information about the history of a Perforce depot. The method marshal.load must be provided with a binary stream (mode='rb') in order to function reliably. Certain changelist descriptions or other elements in a depot history could trigger a premature EOFError, causing the conversion process to fail. This may resolve the issue discussed in the following thread: http://www.selenic.com/pipermail/mercurial/2009-July/026813.html