extensions: move the "import" logic out from "load"
The "load" method does too many things: on-demand import and check version.
This patch moves the import logic out from "load" so it could be wrapped to
change the import behavior, for example, chg will use it to pre-import
extensions.
Testing cloning with the EOL extension
$ cat >> $HGRCPATH <<EOF
> [extensions]
> eol =
>
> [eol]
> native = CRLF
> EOF
setup repository
$ hg init repo
$ cd repo
$ cat > .hgeol <<EOF
> [patterns]
> **.txt = native
> EOF
$ printf "first\r\nsecond\r\nthird\r\n" > a.txt
$ hg commit --addremove -m 'checkin'
adding .hgeol
adding a.txt
Clone
$ cd ..
$ hg clone repo repo-2
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd repo-2
$ cat a.txt
first\r (esc)
second\r (esc)
third\r (esc)
$ hg cat a.txt
first
second
third
$ hg remove .hgeol
$ hg commit -m 'remove eol'
$ hg push --quiet
$ cd ..
Test clone of repo with .hgeol in working dir, but no .hgeol in tip
$ hg clone repo repo-3
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd repo-3
$ cat a.txt
first
second
third
Test clone of revision with .hgeol
$ cd ..
$ hg clone -r 0 repo repo-4
adding changesets
adding manifests
adding file changes
added 1 changesets with 2 changes to 2 files
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd repo-4
$ cat .hgeol
[patterns]
**.txt = native
$ cat a.txt
first\r (esc)
second\r (esc)
third\r (esc)
$ cd ..