git-flow-next (https://github.com/gittower/git-flow-next) uses a
different config schema than legacy git-flow:
gitflow.branch.<type>.prefix instead of gitflow.prefix.<type>.
Recognize both schemas in GetGitFlowPrefixMap by querying each and
merging into a single prefix → branchType map. GitFlowEnabled now
consults the merged map so a next-only setup counts as enabled.
When both schemas configure the same prefix, the legacy entry wins.
In normal usage both schemas agree, so the rule mainly matters as a
deterministic tie-breaker.
Lift the inline parsing in FinishCmdObj into parseGitFlowPrefixMap on
ConfigCommands. The caller now does a direct map lookup against the
parsed prefix → branchType map instead of iterating the raw config
output and suffix-matching. This is preparation for adding git-flow-next
support, which needs to merge a second config schema into the same map.
One incidental change: a branch name without a slash now returns
NotAGitFlowBranch immediately, rather than falling through the
line loop with an empty suffix. Previously a configured
gitflow.prefix.X whose value happened to equal the entire branch
name could match — never a useful outcome.
By constructing an arg vector manually, we no longer need to quote arguments
Mandate that args must be passed when building a command
Now you need to provide an args array when building a command.
There are a handful of places where we need to deal with a string,
such as with user-defined custom commands, and for those we now require
that at the callsite they use str.ToArgv to do that. I don't want
to provide a method out of the box for it because I want to discourage its
use.
For some reason we were invoking a command through a shell when amending a
commit, and I don't believe we needed to do that as there was nothing user-
supplied about the command. So I've switched to using a regular command out-
side the shell there
