test-split: stabilize for Windows
- $PYTHON needs to be quoted when used as an executable in $HGEDITOR. This
avoids the error "'c' is not recognized as an internal or external command".
- seq.py is printing out CRLF, and then the subsequent `sed` script seems to
convert to LF on MSYS. IDK if python print statements can be made to print
LF on Windows, and I'm pretty sure CRLF is baked into some other tests.
- A stray glob was causing the 'obsstore-off' case to report 'no result code
from test'.
- When I ran with --debug, the `hg diff` commands in the test both printed
color sequences, and paused the output as it was run through the pager.