rebase: improve error message for --base being empty or causing emptiness
Before it just said 'nothing to rebase'.
Now 'if "base" is an empty set:
abort: empty "base" revision set - can't compute rebase set
If the set of changesets to rebase can't be found from "base", it will fail as
before but with more explanation of what the problem was.
The name of the "base" option is not obvious - it is more like "samples
identifying the branch to rebase". The error messages for problems with the
specified "base" value will use that term and might thus also not be obvious,
but at least they are consistent with the option name. The name "base" will not
be used if the base only was specified implicitly as the working directory
parent.
Environment setup for MQ
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
Should fail if no patches applied
$ hg qrefresh
no patches applied
[1]
$ hg qrefresh -e
no patches applied
[1]
$ hg qnew -m "First commit message" first-patch
$ echo aaaa > file
$ hg add file
$ hg qrefresh
Should display 'First commit message'
$ hg log -l1 --template "{desc}\n"
First commit message
Testing changing message with -m
$ echo bbbb > file
$ hg qrefresh -m "Second commit message"
Should display 'Second commit message'
$ hg log -l1 --template "{desc}\n"
Second commit message
Testing changing message with -l
$ echo "Third commit message" > logfile
$ echo " This is the 3rd log message" >> logfile
$ echo bbbb > file
$ hg qrefresh -l logfile
Should display 'Third commit message\\\n This is the 3rd log message'
$ hg log -l1 --template "{desc}\n"
Third commit message
This is the 3rd log message
Testing changing message with -l-
$ hg qnew -m "First commit message" second-patch
$ echo aaaa > file2
$ hg add file2
$ echo bbbb > file2
$ (echo "Fifth commit message"; echo " This is the 5th log message") | hg qrefresh -l-
Should display 'Fifth commit message\\\n This is the 5th log message'
$ hg log -l1 --template "{desc}\n"
Fifth commit message
This is the 5th log message