In the change object, the revision number is represented as an integer.
In the download dialog, patchNum is passed as a string. Due to strict
equality comparison, the download schemes for a particular patchset were
never found.
This change parses the patchNum to an int every time an attempt to
compare it is made.
To protect against regressions, all of the mocked patchNum values in the
test suite have been changed to string values to more accurately reflect
the actual data.
Bug: Issue 6224
Change-Id: I3626cda9eaad48c05fb97efd97ba313f20ab5473
b9451ec51c