tests: use proctutil.stdout.write() instead of print() in test-extension.t
I was debugging this test failure on python3 + chg. I get the following hunk as
test failure:
```
@@ -206,6 +206,18 @@ Check normal command's load order of ext
4) bar uipopulate
5) foo reposetup
5) bar reposetup
+ 4) foo uipopulate (chg !)
+ 4) bar uipopulate (chg !)
+ 4) foo uipopulate (chg !)
+ 4) bar uipopulate (chg !)
+ 4) foo uipopulate (chg !)
+ 4) bar uipopulate (chg !)
+ 4) foo uipopulate (chg !)
+ 4) bar uipopulate (chg !)
+ 4) foo uipopulate (chg !)
+ 4) bar uipopulate (chg !)
+ 5) foo reposetup (chg !)
+ 5) bar reposetup (chg !)
0:
c24b9ac61126
```
After hours of debugging and head scracthing, I figured out that something is
wrong with output flushing. I initially switched the print() statements to
ui.warn() but thanks to Yuya who suggested using procutil.stdout.write()
instead.
missing lfs pointer keys: oid, size
ok
unexpected lfs pointer value: version='https://unknown.github.com/spec/v1'
cannot parse git-lfs text: 'version https://git-lfs.github.com/spec/v1\n\noid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393\nsize 12345\nx-foo extra-information\n'
unexpected lfs pointer value: oid='ahs256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393'
unexpected lfs pointer value: oid='4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393'
unexpected lfs pointer value: size='0x12345'
ok
cannot parse git-lfs text: 'version https://git-lfs.github.com/spec/v1\noid sha256:4d7a214614ab2935c943f9e0ff69d22eadbb8f32b1258daaa5e2ca24d17e2393\nsize 12345\nx-foo extra\ninformation\n'
unexpected lfs pointer key: x_foo
missing lfs pointer keys: oid
missing lfs pointer keys: oid, size