Explicitly separate test-suite rpmdb reset from test initialization

Many of our tests require RPMTEST_INIT to create a writable snapshot,
but especially after c17cc69,
relatively few require initializing or resetting the rpmdb in the image.

Separate the two and explicitly call RPMDB_RESET (renamed from RPMDB_INIT
for a clean break) where it is actually needed. The common pattern that
emerges is: build several packages at once and then do various things with
it. Each of these RPMDB_RESET uses is actually somewhat problematic because
whenever it's required there's a chance that previous tests could affect
the results. Can't help that just now, but at least we've identified the
issue.

Besides making the needs and usages clearer, this introduces a nice fat
speed boost for the test-suite - on my laptop, from 2m 50s to 2m 20s.

tests/README.md

@@ -138,7 +138,7 @@ as well as the existing tests.  Below are the specifics of RPM's test-suite:
 * Use `RPMTEST_SETUP` instead of `AT_SETUP`
 * Use `RPMTEST_CHECK` instead of `AT_CHECK`
 * Use `RPMTEST_CLEANUP` instead of `AT_CLEANUP`
-* Use `RPMTEST_INIT` or `RPMDB_INIT` to create a mutable snapshot (optional)
+* Use `RPMTEST_INIT` to create a mutable snapshot (optional)
     * The absolute path to the snapshot's root is stored in the `$RPMTEST`
       environment variable, modify the directory tree as you wish
     * To run RPM inside the snapshot, use the `runroot` prefix, e.g. `runroot
@@ -155,6 +155,7 @@ as well as the existing tests.  Below are the specifics of RPM's test-suite:
     * You can create a custom user (or users) by supplying a list of usernames
       to the macro, e.g. `RPMTEST_USER([user1, user2])`.  Then, use
       `runroot_user -n <name>` to run a binary as a specific user
+* Use `RPMDB_RESET` to reinitialize a snapshot to an empty rpmdb (avoid this)
 * If no snapshot was used, just call the RPM binaries normally
 * Store any working files in the current directory (it's always writable)
 

tests/local.at

@@ -15,11 +15,6 @@ rm -rf "${RPMTEST}"`rpm --eval '%_dbpath'`
 runroot rpm --initdb
 ])
 
-m4_define([RPMDB_INIT],[
-RPMTEST_INIT
-RPMDB_RESET
-])
-
 m4_define([RPMPY_RUN],[[
 cat << EOF > test.py
 # coding=utf-8
@@ -72,7 +67,6 @@ m4_define([RPMPY_TEST],[
 RPMTEST_SETUP([$1])
 AT_KEYWORDS([python])
 setup_env
-RPMDB_INIT
 RPMPY_CHECK([$2], [$3], [$4])
 RPMTEST_CLEANUP
 ])