obsolete: refactor writemarkers to only encode them
The function is now able to write the version header as necessary. The function
now yield bytes to be written to a stream.
This should ease later use of this function for wireprotocol based exchanged.
Prepare the public use of the writemarker by wireprotocol function.
hg debuginstall
$ hg debuginstall
checking encoding (ascii)...
checking installed modules (*mercurial)... (glob)
checking templates (*mercurial?templates)... (glob)
checking commit editor...
checking username...
no problems detected
hg debuginstall with no username
$ HGUSER= hg debuginstall
checking encoding (ascii)...
checking installed modules (*mercurial)... (glob)
checking templates (*mercurial?templates)... (glob)
checking commit editor...
checking username...
no username supplied (see "hg help config")
(specify a username in your configuration file)
1 problems detected, please check your install!
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