Conflicting 'paperpi.ini' configs causes a weird behavior

Start with get_config_files in paperpi/paperpi.py and the Screen class, comparing how the two paperpi.ini files are applied before the first clear-screen operation. Done means the screen uses the intended driver from the effective configuration and clears successfully when the files specify different screen types.

I ran into a weird bug where if two config files have different screens, the first few operations will run on the wrong driver/screen config and then by the time the first plugin is displayed, it works as intended. I was able to replicate the issue (after fixing it). It's also likely not a high impact bug since I'm sure the percentage of people running two different screens on the same device is small. Anyway, here are the details and steps to reproduce...

Issue found: The first "clear screen" operation in the Screen class does not complete successfully when two different screen types are listed in two separate paperpi.ini files. I was using a 4.2" yellow screen on a 32-bit Pi4 running buster. It's not a fresh install and there might be some issues with how I'm running the PaperPi application, but I wanted to at least document it.

Console output:

pi@raspberrypi:~/github/PaperPi $ python paperpi/paperpi.py
18:51:40 paperpi :get_config_files:213 :DEBUG      - gathering configuration files
18:51:40 paperpi :get_config_files:249 :INFO       - using configuration files to configure PaperPi: [PosixPath('/home/pi/github/PaperPi/paperpi/config/paperpi.ini'), PosixPath('/home/pi/.config/com.txoof.paperpi/paperpi.ini')]
18:51:40 paperpi :main      :622 :INFO       - ********** PaperPi 0.3.0.0 Starting **********
18:51:40 paperpi :main      :623 :DEBUG      - configuration:
{'main': {'display_type': 'waveshare_epd.epd4in2c', 'vcom': 0.0, 'max_refresh': 4, 'log_level': 'DEBUG', 'splash': False, 'rotation': 0, 'daemon': False}, 'Plugin: default fallback plugin': {'layout': 'layout', 'plugin': 'default', 'refresh_rate': 30, 'min_display_time': 60, 'max_priority': 32768}, 'Plugin: Reddit Quotes': {'layout': 'layout', 'plugin': 'reddit_quote', 'refresh_rate': 100, 'min_display_time': 50, 'max_priority': 2, 'max_length': 144}, 'xPlugin: Librespot': {'layout': 'layout', 'plugin': 'librespot_client', 'refresh_rate': 10, 'max_priority': 0, 'min_display_time': 15, 'player_name': 'SpoCon-Spotify', 'idle_timeout': 10}, 'Plugin: Moon Phase': {'layout': 'layout', 'plugin': 'moon_phase', 'min_display_time': 30, 'max_priority': 2, 'email': '[email protected]', 'location_name': 'Europe/Amsterdam', 'lat': 52.3, 'lon': 4.9}, 'xPlugin: LMS - Your Player Name': {'layout': 'layout', 'plugin': 'lms_client', 'player_name': 'Your Player Name', 'refresh_rate': 5, 'min_display_time': 30, 'max_priority': 0, 'idle_timeout': 15}, 'xPlugin: Basic Clock': {'layout': 'layout', 'plugin': 'basic_clock', 'refresh_rate': 30, 'min_display_time': 50, 'max_priority': 2}, 'Plugin: XKCD Comic Plugin': {'layout': 'layout', 'plugin': 'xkcd_comic', 'refresh_rate': 1200, 'min_display_time': 120, 'max_x': 800, 'max_y': 600, 'resize': 0, 'max_retries': 10, 'max_priority': 2}, 'xPlugin: Word Clock': {'layout': 'layout', 'plugin': 'word_clock', 'refresh_rate': 125, 'min_display_time': 255, 'max_priority': 2}, 'xPlugin: A Demo Plugin': {'layout': 'layout', 'plugin': 'demo_plugin', 'min_display_time': 30, 'max_priority': 1, 'your_name': 'Slartybartfast', 'your_color': 'chartreuse'}, 'xPlugin: New Yorker Comic': {'layout': 'layout', 'plugin': 'newyorker', 'day_range': 5, 'refresh_rate': 120, 'min_display_time': 60, 'max_priority': 2}, 'xPlugin: Weather Adis Ababa': {'layout': 'layout', 'plugin': 'met_no', 'refresh_rate': 300, 'min_display_time': 40, 'max_priority': 2, 'location_name': 'Adis Ababa', 'lat': 9.0, 'lon': 38.75, 'email': '[email protected]'}, 'Plugin: Crypto Bitcoin v USD': {'plugin': 'crypto', 'layout': 'layout', 'fiat': 'usd', 'coin': 'bitcoin', 'days': 14, 'interval': 'hourly', 'rss_feed': 'https://bitcoinmagazine.com/.rss/full/', 'min_display_time': 30, 'refresh_rate': 300, 'max_priority': 2}, 'xPlugin: decimal binary clock': {'layout': 'layout', 'plugin': 'dec_bin_clock', 'refresh_rate': 30, 'min_display_time': 50, 'max_priority': 2}, '__cmd_line': {'list_plugins': False}}


18:51:40 Screen  :_loadEPD  :373 :DEBUG      - configuring omni_edp.waveshare_epd.epd4in2c
18:51:40 Screen  :epd       :312 :DEBUG      - epd configuration waveshare_epd.epd4in2bc
18:51:40 Screen  :rotation  :359 :DEBUG      - rotation=0, resolution=[400, 300]
18:51:40 Screen  :wrapper   :247 :DEBUG      - initing display
18:51:40 epd4in2bc:ReadBusy  :70  :DEBUG      - e-Paper busy
18:51:40 epd4in2bc:ReadBusy  :73  :DEBUG      - e-Paper busy release
18:51:40 Screen  :clearEPD  :398 :DEBUG      - clearing screen
18:51:41 epd4in2bc:ReadBusy  :70  :DEBUG      - e-Paper busy

First few lines of /etc/default/paperpi.ini:

# CONFIG_VERSION=1
[main]
# waveshare display type use HD for IT8951 displays
display_type = waveshare_epd.epd7in5b_V2

First few lines of /home/pi/.config/com.txoof.paperpi/paperpi.ini:

# CONFIG_VERSION=1
[main]
# waveshare display type use HD for IT8951 displays
display_type = waveshare_epd.epd4in2c

Changing the /etc/default/paperpi.ini to the waveshare_epd.epd4in2c driver fixes the issue.