rebase: improve error message on improper phases
The previous error message had two issues: The first issue was that it
wasn't, in fact, an error but a warning, even though it described a
fatal error condition preventing the successful completion of the
command. The second was that it didn't mention the immutable
changesets, leaving the user guessing at the true cause of the error.
The main downside to this change is that we now get an 'abort: can't
abort...' message which technically contradicts itself. In this case,
I blame that on the two uses we have for the word; if it weren't for
backwards compatibility, we could make util.Abort print out 'error:
<whatever>'.
Test the CIA extension
$ cat >> $HGRCPATH <<EOF
> [extensions]
> hgcia=
>
> [hooks]
> changegroup.cia = python:hgext.hgcia.hook
>
> [web]
> baseurl = http://hgserver/
>
> [cia]
> user = testuser
> project = testproject
> test = True
> EOF
$ hg init src
$ hg init cia
$ cd src
$ echo foo > foo
$ hg ci -Amfoo
adding foo
$ hg push ../cia
pushing to ../cia
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
<message>
<generator>
<name>Mercurial (hgcia)</name>
<version>0.1</version>
<url>http://hg.kublai.com/mercurial/hgcia</url>
<user>testuser</user>
</generator>
<source>
<project>testproject</project>
<branch>default</branch>
</source>
<body>
<commit>
<author>test</author>
<version>0:e63c23eaa88a</version>
<log>foo</log>
<url>http://hgserver/rev/e63c23eaa88a</url>
<files><file uri="http://hgserver/file/e63c23eaa88a/foo" action="add">foo</file></files>
</commit>
</body>
<timestamp>0</timestamp>
</message>
$ cat >> $HGRCPATH <<EOF
> strip = 0
> EOF
$ echo bar > bar
$ hg ci -Ambar
adding bar
$ hg push ../cia
pushing to ../cia
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
<message>
<generator>
<name>Mercurial (hgcia)</name>
<version>0.1</version>
<url>http://hg.kublai.com/mercurial/hgcia</url>
<user>testuser</user>
</generator>
<source>
<project>testproject</project>
<branch>default</branch>
</source>
<body>
<commit>
<author>test</author>
<version>1:c0c7cf58edc5</version>
<log>bar</log>
<url>http://hgserver/$TESTTMP/cia/rev/c0c7cf58edc5</url>
<files><file uri="http://hgserver/$TESTTMP/cia/file/c0c7cf58edc5/bar" action="add">bar</file></files>
</commit>
</body>
<timestamp>0</timestamp>
</message>