git-request-pull.sh: remove -e switch to shell interpreter which breaks ksh

git-request-pull.sh: remove -e switch to shell interpreter which breaks ksh

The -e option causes the shell to exit immediately when a command exits
with a non-zero exit status.  This does not seem to cause a problem for
Bash, but it does cause a problem for the Korn shell, like Solaris's
xpg4/sh, whose unset utility returns non-zero if it is passed a variable
name which was not previously set.  When using xpg4/sh, git-request-pull
exits while sourcing git-sh-setup since git-sh-setup tries to unset the
CDPATH environment variable.

When git-request-pull was originally written, it did not do any error
checking and it used this shell feature to exit when an error occurred.
This script now performs proper error checking and provides useful error
messages, so this -e option appears to be merely a historical artifact and
can be removed.

Kudos to Jonathan Nieder for introducing t5150 which exercises the
request-pull code path.

Suggested-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>