contrib: don't hardcode path to bash interpreter
Use the env binary to figure out the correct bash to use.
Certain systems ships with an ancient version of bash, but the
user might have installed a newer one that is earlier in $PATH.
For example the current version of Mac OS X ships version 3.2.51
of bash, which does not understand new fancy builtins such as
readarray. A user might install a newer version of bash, use that
as their shell and add that path before bin.
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>
$ cd ..