resolve: do not crash on empty mergestate
I managed to get an empty .hg/merge/state file by interrupting a merge
by pressing Control-C. This lead to this error:
TypeError: a2b_hex() argument 1 must be string or read-only buffer,
not None
since localnode is assigned None before the iteration over lines in
the mergestate begins.
adding .hgignore
adding a
% invalid eol
applying eol.diff
abort: Unsupported line endings type: LFCR
% force LF
applying eol.diff
'a\nyyyy\ncc\n\nd\ne'
% force CRLF
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
applying eol.diff
'a\r\nyyyy\r\ncc\r\n\r\nd\r\ne'
% auto EOL on LF file
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
applying eol.diff
'a\nyyyy\ncc\n\nd\ne'
% auto EOL on CRLF file
applying eol.diff
'a\r\nyyyy\r\ncc\r\n\r\nd\r\ne'
% auto EOL on new file or source without any EOL
applying noeol.diff
'noeol\r\nnoeol\n'
'neweol\nneweol\r\n'
adding b
% binary patch with --eol
applying bin.diff
'a\x00\nc\r\nd'