phabricator: rework phabread to reduce memory usage and round-trips
This patch reworked phabread a bit so it fetches the lightweight
"Differential Revision" metadata for a stack first. Then read other data.
This allows the code to:
a) send 1 request to get all `hg:meta` data instead of N requests
b) patches are read in desired order, no need to buffer the output
"b)" reduces the memory usage from O(N^2) to O(N) since we no longer keep
old patch contents in memory.
The above `N` means the number of patches in the stack.
running: init test1
result: None
running: add foo
result: 0
running: commit -m commit1 -d 2000-01-01 foo
result: None
running: commit -m commit2 -d 2000-01-02 foo
result: None
running: log -r 0
changeset: 0:0e4634943879
user: test
date: Sat Jan 01 00:00:00 2000 +0000
summary: commit1
result: None
running: log -r tip
changeset: 1:45589e459b2e
tag: tip
user: test
date: Sun Jan 02 00:00:00 2000 +0000
summary: commit2
result: None