[Bug-stow] Tree folding and --dotfiles do not cooperate

[Ian Ford]

Tree folding does not work properly when package is stowed using --dotfiles and
contains dot-XXXX directory if the target already has a .XXXX directory:
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$ tree -a ..
..
├── .hidden
└── stow
    └── pkg
        └── dot-hidden
            └── file

4 directories, 1 file

$ stow --dotfiles pkg
stow: ERROR: stow_contents() called with non-directory path: stow/pkg/.hidden
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Verbose output:
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$ stow --dotfiles --verbose=3 pkg
stow dir is /home/ngenisis/target/stow
stow dir path relative to target /home/ngenisis/target is stow
cwd now /home/ngenisis/target
cwd restored to /home/ngenisis/target/stow
cwd now /home/ngenisis/target
Planning stow of package pkg...
Stowing contents of stow/pkg (cwd=~/target)
Stowing stow / pkg / .hidden
Stowing contents of stow/pkg/.hidden (cwd=~/target)
stow: ERROR: stow_contents() called with non-directory path: stow/pkg/.hidden
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Version and system information:
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$ stow --version
stow (GNU Stow) version 2.3.1

$ perl -v

This is perl 5, version 30, subversion 0 (v5.30.0) built for
x86_64-linux-thread-multi

Copyright 1987-2019, Larry Wall

Perl may be copied only under the terms of either the Artistic License or the
GNU General Public License, which may be found in the Perl 5 source kit.

Complete documentation for Perl, including FAQ lists, should be found on
this system using "man perl" or "perldoc perl".  If you have access to the
Internet, point your browser at http://www.perl.org/, the Perl Home Page.

$ uname -a
Linux thinkpad 5.2.13-arch1-1-ARCH #1 SMP PREEMPT Fri Sep 6 17:52:33
UTC 2019 x86_64 GNU/Linux
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