date: fix parsing months
Thanks nemo for discovering this on #mercurial IRC channel.
Test Plan:
Add a test. It fails before this patch:
```
+ hg: parse error: invalid date: 'Feb 2018'
+ hg: parse error: invalid date: 'Apr 2018'
+ hg: parse error: invalid date: 'Jun 2018'
+ hg: parse error: invalid date: 'Sep 2018'
+ hg: parse error: invalid date: 'Nov 2018'
```
Differential Revision: https://phab.mercurial-scm.org/D2289
# Extract version number into 4 parts, some of which may be empty:
#
# version: the numeric part of the most recent tag. Will always look like 1.3.
#
# type: if an rc build, "rc", otherwise empty
#
# distance: the distance from the nearest tag, or empty if built from a tag
#
# node: the node|short hg was built from, or empty if built from a tag
gethgversion() {
export HGRCPATH=
export HGPLAIN=
make cleanbutpackages
make local PURE=--pure
HG="$PWD/hg"
"$HG" version > /dev/null || { echo 'abort: hg version failed!'; exit 1 ; }
hgversion=`LANGUAGE=C "$HG" version | sed -ne 's/.*(version \(.*\))$/\1/p'`
if echo $hgversion | grep + > /dev/null 2>&1 ; then
tmp=`echo $hgversion | cut -d+ -f 2`
hgversion=`echo $hgversion | cut -d+ -f 1`
distance=`echo $tmp | cut -d- -f 1`
node=`echo $tmp | cut -d- -f 2`
else
distance=''
node=''
fi
if echo $hgversion | grep -- '-' > /dev/null 2>&1; then
version=`echo $hgversion | cut -d- -f1`
type=`echo $hgversion | cut -d- -f2`
else
version=$hgversion
type=''
fi
}